Why its give me Black screen with blue edges and vice versa every time

Hi @bx44

The power board seems to be OK as it turns on and there's backlighting. You could always inspect it for any obvious component damage e.g. blown capacitors or heat stressed components etc.

I think though that there's a mainboard problem.

Here's a teardown guide that shows how to disassemble the monitor that may help.

Try replacing the mainboard (supplier example only) and check if that resolves the problem.

If you decide to do this, verify that the board you order has the same model number or part number as the original. Usually this is found either printed on the board or on a sticker on the board