Envy X360 Won't boot after battery replacement

[VPTech65]

I replaced the main battery in my landlord's Windows 10 HP Envy X360 convertible Sunday. I got the usual cmos 505 error because the main battery also powers the cmos and there is no separate backup battery like on most newer ones.  After replacing it, windows won't fully load. I get a black screen with a spinning circle for a long time and eventually a mouse pointer on the black screen but nothing else. Ctrl alt del or any other key sequence are unresponsive. I checked the bios settings, reset the time and date, tried secure boot both enabled and disabled to no avail.  It won't even boot in safe mode from the recovery menu. I even went as far as trying the reset this pc option reinstalling Windows, both trying saving and not saving user data and both ended on a blue screen saying it could not be reset and no changes were saved. So I don't know if there's a messed up setting in the bios I'm not seeing or if the hard drive coincidentally failed at the same time I did the battery change.  I even pulled the new battery back out and powered it up with just the adapter and it still does the same thing.  Does anyone know what to do to get it working again?

[VPTech65]

Update:  I ran the extensive system tests overnight and everything passed including the RAM and hard drive extensive test so I don't believe it's a hardware issue.  However I noticed something that may be causing the problem.  I've manually set the system date and time in the bios at least twice since changing the battery, most recently just before running the diagnostics last night.  But I noticed this morning that it's way off again.  The date is 10/18/7967.  I read somewhere that the system date being way off can cause boot issues so maybe that's it?  It keeps going to one day past the current day with the year of 7967.  Does anyone know how to fix that?  The battery is installed and it hasn't even been powered down since I set it last night yet it changed.