Replace the size 2032 CMOS battery if it hasn't been done in the last 5 years.  A low battery will cause all sorts of bizarre problems, including boot issues.  Duracell or Energizer is suggested as Sony only lasted me 2 years.  Better deals on Amazon than in store. I'd definitley want to try that first.
I have an old 7010 i5 3570 that is used once or twice to run a 32-bit account app and little else. Yes it's an old box, but not sure I want to buy new just for the accounting suite or take the hit of moving to a cloud solution and having to completely change the way we use an accounting suite. So really just trying to coax this thing along. I posted about this issue some time back and got advice of: The machine suffers two issues Once started there are ZERO issues. I had wondered about NVM and a motherboard battery, bt no comments on that theory. Hibernating rather the Shut down does seem to give a better chance of a restart next time around. Remember too, only used once or twice a month and so stands powered off (or hibernated) for days or weeks on end. The machine was shipped with 1x 4GB RAM and I upgraded this to 2x 8GB ("16GB kit (2 x 8 GB) for Dell Optiplex 7010 (PC3 12800U) Memory Module RAM" from Amazon (SiQuell)). I did not get these issues prior to the memory update ... just a very slow machine. The memory is claimed to be specifically for a 7010 but might a memory incompatibility be the cause? Note it does eventually recognise everything and this past week when it was coaxed into life I found re-seating the RAM and SATA lead resulted in 'no disk' to booting properly, so could it be a duff SATA cable or connection? Previous suggestions included rebuilding Win10 etc., however, these problems seem well before Win10. At the bios level it doesn't seem to be recognising an HDD even those it has a new drive and once it's persuaded to crank up, happily runs without any form of issue. So yes I know it's an old box. Yes I know it's 'only' a 4 core i5 without hyper-threading, but it is more than adequate to run a 32 bit accounting suite once a month which is its sole purpose in life. Any ideas other than check it out and either 'go cloud' or buy another unit? NVM battery?
Optiplex 7010 doesn't recognise HDD or powers off during start-up