@jimit Thanks for the Edit pointer and feedback. Good info about the power button too (like most guys, I look at manuals after I bang my head on the wall a bit).

One update - I had separated the modules to take a look a the 850 mAhr batter board earlier today. Ended up having fits getting the M5Stack to work again when I re-stacked - even with just the bottom board and core and having the spacer on the bottom board pressed all the way down. I ended up reverting to just removing the pin spacer (that was a PIA) to see if that helped. I did manage to get things working again but it took some fussing. End of the day, I think it comes down to tolerance accumulations on the pin header, socket header, plastic assemblies and then is compounded by the tapers on the male pins.

@pkourany - I feel your pain. I have pretty well isolated the issues with mine (Basic) to the pin and header connections for the MBus connecting the core (main) board with the sub-boards and base. After posting earlier, I actually took my bottom plate off and pulled the 850mah battery holder to check a few things related to some secondary circuits I am designing. I had fits getting everything to work again.

The stacking idea is a nice approach, but as an ME what I am seeing are tolerance issues with engagement of the male pins into the female sockets. I think there is a luck of the draw thing going on. There are mechanical tolerances on the pins and headers which will have variations from set to set. The same applies for the housings. Some of us just seem to have those at the extremes and end up with dicey header connections. The other compounding challenge tied to the pins seating is that all the male pin ends are tapered to help guide into the sockets - makes getting solid contact in the header all the more a variable thing.

I am in the process of looking at other ways to skin that particular cat and will let you know if I come up with something. Of course, one thing that helps me is that I have a different form factor in mind for how I want to integrate things and may be able to avoid. It's tough coming up with a stacking header system in such a small form factor as the M5Stack.

I think you will really like the device once you get past the issues you are having like some of the rest of us. It really is a nice setup and I am hoping that some of the growing pains and feedback work into better solutions for the next editions. Sucks a bit dropping the coin for one only to have to fuss with it to get some basic things to work.

JimiT noted that the manual states you may need to hold the power (red) butting in while flashing. Haven't tried that myself yet but that may be a short term option. If you get a clearer image of the board so I can read the SOIC chips, I'd help identify the ground points.

Slightly shorter male pins exposed (I thought the word, it just didn't make it to the fingers)

Interesting information. I only have the one device here so can't say if the "fixes" that have worked are universal. I just put together an image to help illustrate what I was talking about on the header pins for another post.

I will reiterate that the noted plastic spacer on the bottom board, proto board, and 850mAh battery expansion I have were not fully seated. This resulted in slightly male pins (0.5 mmm give or take) and intermittent connections with the female headers in the MBus stack. The plastic spacer being up also acted as a stop preventing full engagement with the female sockets in the header and resulted in programming problems, use of the capacitor on the RST\GND thru the base plate, and power feed problems to the Core from the base and battery packs. While I haven't used them, I suspect I'd have had intermittent issues with all other pin functions thru the header stack without my little tune up :)

Again, may not be a universal thing since I only have one system but I'd highly suggest anyone using the system take a few moments to seat the space shown on the assorted board. My suspicion is that part of RMR's issues sound related to the pin engagement and is why it works when the base (or other boards) are pulled off.

Needless to say, let us all know how you make out :) Also, the above should work but I'll warn you that I am a ME and can cause issues with EE stuff :)

With regard to a "permanent" capacitor, I think you have a few options. Cross check to the schematic on different ground points. That is located here: https://github.com/m5stack/M5-hardware/blob/master/M5_Core_SCH(20171206).pdf

My first thoughts for you are as follows:

Please note that I have not dug into the SOIC chips to identify which pin is GND. I can't really make them out in your photo to identify which is which and correctly identify the ground pins that are candidates for the other connection. You'll need to check the chips and ID the ground pin or just go to the USB shield (after confirming it's tied to GND). you could possibly tie over to the grove header GND pin. Probably better to keep the capacitor whips (insulated wires I suggested) as short as possible and tie to either the MBus GND or one of the close SOIC's.

I am surprised that the shield was omitted on your board over the ESP32. It would be interesting to know if that is the case on all of that particular model. Can you advise if yours is the "newest" 2018 version with the PSRAM and IMU?

A couple of thoughts\suggestions for you. First, if you want to keep using the GND and RST on the base plate, your issue may be with the pins of the base plate (and\or any expansions) fully mating with the M-Bus header in the core unit. The plastic male header spacer on my base plate (as well as on a prototype and battery expansion) all were not fully seated. This basically shortened the pins and acted to limit the engagement of the pins with the Core MBus header and caused problems with the reset capacitor working as well as battery power feeding the Core board. The quick remedy that fixed that was to gently press the plastic space all the way down on the male pins. This appears to have given much better seating of the male pins into the female headers. See image:

@jimit hope I didn't mess up your link. First time working with setting up my own things on GitHub. The revised link seems to work fine from here now:

https://github.com/KenTinker/M5Stack-Prototype-ACAD-Files

@jimit I figured that part out but not quite how to rename.

@kentinker That doesn't work either. I shouldn't have cursed IE. Looks like the issue may have been me adding in a '-' when I setup the GitHub repository. Couldn't figure out how to rename it, so I made a new one. Knock on wood this link works:
https://github.com/KenTinker/M5Stack-Prototype-ACAD-Files