Dell R720 No boot

Hey all, I have a Dell R720, DP/N 0X3D66 which was working fine for the last year. Recently during a routine update i was unable to get it to post into my OS (Ubuntu server). After this happened i also couldn’t get into my IDRAC. The server turns on and I can get into PXE network boot but that’s it. F2 does nothing to enter bios and it gets stuck and hangs if i do nothing. Have stripped it back to one cpu ram and psu to no avail. open to ideas, don’t wanna throw the server out!!