Hi, I have a problem with my dell optiplex 755. I once shut down it properly but on the next day it won't power up as usual but gives a blinking amber LED when power on. Can anyone assist, is this cause from a power supply unit failure or something else?
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That power supply might be the cause. Have you checked your battery if it's in good working condition?
Try removing the battery pack and use external power cord. It could be from the batteries.