Computer will not post

[MatchuEnsmith]

I just got my SSD back from my friend who was installing something for me (I have terrible WiFi speed) and now my PC won't post. The PC turnes on but doesn't send power to peripherals and the monitor doesn't receive any signal. The on board led debugger says error code 55 for memory not installed but it clearly is and to be sure I have reseated it and cleared CMOS. I have checked for bios updeates and reseated every cable. The PC also revvs the fans up to max when started and requires the power button to be held down for many seconds before shutting off rather than one press. I have an Intel 6600k on an Asus Maximus hero lga 1151 board with 16gb of coraair vengance led ram, I also have a 1 tb wd black and an 850 Evo 500gb. My CPU has water cooling and my GPU is an Rx580 8gb from Asus. The power supply is a Corsair RMx 750x. And I have Windows 10 64bit. Plz help I have tried everything on the pinned forums to no avail.