How to detect if faulty device? V4 - 2.13inches HAT

[raffobaffo]

I bought 2 2.12inches epaper displays, one with 3 colours, one with 2 colours.
I use them with an esp8266, following the schema provided here. For both boards, I can't update (anymore) the screen. They both worked for approx one minute with the example code in C (Arduino IDE) and then, puff. Stopped working totally, hours of trying, nothing works.
I am returning the two, and I don't want to buy more if I can't make sure they work.. How can I test for faulty units? Is there something special about v4?