Installed Common Sense:
Before testing please make sure your CPU, memory is working, you can try it on other computers to make sure they are working.Don’t put all the accessories on it at one time. You can try the CPU, memory and screen first.

Whether the Caps lock button works or not is the dividing line for the motherboard to work or not. If the Caps lock button can be switched, the CPU, memory and motherboard are basically determined to work. At this time, attention should be paid to the LED display problem.The most important is that all accessories must be removed in the absence of electricity, otherwise it may burn out the accessories.
1、Switch working. means motherboard working. please check screen.
2、Can’t switch. please check CPU and ram.

3   No Power No Display No warranty

4  1 month warranty other isue