PSU Alternates between Green and Orange when plugged in and console doesn’t turn on.

Story so far: I am on vacation and was using my 360 (although with a different power supply) days before I packed it up. The power supply I packed with me was used as a secondary when I wanted to take my 360 to my racing wheel setup and was always working fine (although I didn’t test it prior to packing it up and was last used about 2-3 months before I packed it, before packing it it was unplugged sitting next to the racing sim monitor) it’s been a couple of days since I arrived and I went to plug it in only to find it doing this. Rarely the button may become green but the PSU will always alternate and never stay on green. Any help would be appreciated, thanks.