Looks like you did many different things.  Try unplug power cord, depress power button for 30 sec, replace cmos battery with a new battery cr2032 and clear cmos settings via motherboard jumper.
I was wanting to perform a clean install of Win 11. I first created a USB drive using the media creation tool from Microsoft. After having the USB, I inserted the drive and restarted the PC, then selecting the F12 key. The system ignored the F12 key. I tried several times. The F2 key also did nothing. I then tried the Support Assist software. I created a new USB drive but once again the F12 key would not give me the boot menu. I then tried to select the Advanced Startup from the Recovery setting in Windows. The PC would not go into the Advanced Startup and would just give me a blank screen. I then tried Reset This PC from the Recovery settings.  This time the PC started to download Windows but then said something went wrong and the reset could not finish. I then ran MSCONFIG.exe and selected Safe mode. Now I have a computer that will not boot at all. The F2/F12 keys do not work, the Dell logo never appears and all I see is a blank screen. Can someone offer some guidance as to how I can get to a working system again? Thank you in advance. 
XPS 8930, clean install, will not boot