AtomDisplay Waveshare 5inch

[HappyUser]

I connected this display to the out of the box M5AtomDisplay. The display immediately showed the sample graphics. So everything is working.
Than I tried to upload the AtomDisplay_Factory to the Atom. Played around with some display setting but can't get it to work anymore. The display shows no graphics at all. The backlight is on though. Who know which settings for this display : https://www.waveshare.com/wiki/5inch_HDMI_LCD. It is a 5 inch HDMI display with 800*480 pixels. Thanks

A further issue that makes me wonder. I have purchased two AtomDisplays from the same vendor at the same time. So I assume that they both have the same version of software factory uploaded. I run the clean one (so with the default factory settings), and my display works. I upload the Atomfactory from the sample files (GitHub) on my second AtomDisplay and nothing shows up. So this is weird. Help is appreciated.

Note 2 : with this wave share 7 inch display, also the sample factory software works okay. https://www.waveshare.com/wiki/7inch_HDMI_LCD_(C)

So what is so special about the setting for the wave share 5 inch display?