Last night my Precision 7530 was not plugged in and ran out of battery while an external USB hard drive was still connected.  I have not been able to boot it since.  I have had issues before when failing to safely eject an external HD but was then able to recover somehow.  This time I am not so lucky.  On boot the laptop is stuck at the Dell logo and clocking.  I'm looking for recommendations on how to approach this issue.

So far I have factory reset the BIOS settings
I've used the OS recovery tool under the F12 boot menu to restore from a prior restore point
I'm currently using that tool to scan hardware (but that looks like it might take the remainder of the day based on it's slow progress).

I would like to avoid wiping the system and starting clean if I can.  Not sure what files I might lose if I did that.

Thanks for your input.