I am a newbie so please help on this one.

I purchased the first printer in Nov 2020, set it up tried printing and it managed 4 prints. Had an extra SD card and loaded several more .gcode files. Inserted it in the slot, switched on but the screen showed a blank rectangle in the centre whilst the main power pack and fan ran ok. the processor was dead although I spied a working blue led through the fan slots. Because the screen was dead I snt the unit back to Amazon assuming there was just a fault.

The new one arrived and after rebuilding exactly the same fault occured.sent it back to Amazon. A replacent was duly sent, built up, tested and failed after 5 hours printing. Amazon could not understand the problems so suggested I contact Creality.

Over to a kind person on your forum who hopefully can help. I should say that it seems unlikely that there is a compnent fault, more than likely it is a fault of mine. In the manual thereis mention of a RESET condition but unable to find where or what.

Please help.

power switches off after new micro SD card inserted. I am a newbie to this and have purchased an Ender 3D from Amaxon. So far I have replaced each 3 times with a replacement but still it happens. The printer operates for about 5 hours on the original card. When I try to load up extra gcode files on a new microSD file then the printer will not boot up. In fact thescreen shows a darkened rectangle in the middle. The main power pak fan operates and there is a blue led visible in the processor. but no fan working. It seems obvious that it must be something I have done ,or not done, as you don't have that exrensive failure rate. The manual does seem to infer that there is a RESET available but haven't found it. Need help please. I will say that Amazon have been very good at supplying new replacements but they are lacking in the knowledge of these units.