Print bed damage causing warping issues?

So I’m pretty new to 3D printing. I spent most of the summer learning and playing around with a Taz 5 and decided to actually buy a machine of my own, so I picked up a used Mini for a great price. I was expecting it to have some wear, but it seems that there is actually some damage to the print bed itself, and I’m having some real issues getting the HIPS I’m using right now to stick to the print bed.

So this is kind of a two-fold question - a) what kind of damage is this? Is it just to the PEI surface or actually to the glass bed? It feels pretty deep but I’m not sure how thick the PEI sheet actually is - plus I would think the bed would have cracked with a dent like that in it. and b) would replacing the PEI sheet kind of fill over it and fix it if it does go down to the glass?

I’m currently running through other troubleshooting to get my prints to stick to the bed better right now. I’ve cleaned the bed and I’m working on adjusting Cura settings to see if any of that helps. The printer otherwise seems in great condition, and prints Rockotpuses (rocktopi?) perfectly. I’ve included some pictures of a calibration cube I printed. It prints the middle layers fine, but there’s issues (I assume due to warping) on the bottom and then mysteriously on the very top layer too.

Print Bed Damage

Calibration Cube Issues

P.S. anyone know how to make these images smaller in the BBCode, I tried the usual tags and can’t seem to get them to be anything but massive.

The rings look like the nozzle was initially too low… probably because the auto-leveling was faulty - because of a dirty nozzle or disc preventing the proper light touch to establish continuity. Check the nozzle and corner discs for any leftover filament and check the wiper pad (flip it over or replace). A light sanding should remove the rings (use a fine grit for finishing)… sand the entirePEI surfaceto keep it even.

The divot below the rings looks like the nozzle melted the PEI… Pretty much un-fixable.

The PEI seems to have protected the glass bed. I’d replace the PEI. Tips to remove the PEI.

Also make sure to watch the auto-level process. Make sure the bed doesn’t deflect downward. This will lead to print issues and possibly the nozzle digging into the bed again.