Metal screech after RMS and flexplate check... HELP!
 

Guys I am at a loss and need help.
I decided to replace the rear main seal (leaking) on my stock 2000 XJ 2WD. No lift. Only jack stands. I go through the RMS part and what a pain that was and putting the oil pan with new gasket was a real chore.
While I was down there and before I put the oil pan back in place, I figured I should check the flexplate bolts. I watched quite a few YT vids and it seemed pretty straight forward. I took the inspection plate off and checked the first bolt that was there. No problem.
I wondered "How am I going to rotate the flexplate? From YT videos, I learned of two methods, 1 to put a socket wrench on the crank and rotate it. 2 use a screw driver and use the trans bell bolt as base and lever the screwdriver to rotate the flexplate.
Since I was working alone, I didn't want to have to go back and forth to the crank so I used the screw driver method. Worked fine. All bolts were surprising tight after 19 years. Cool! I put the oil pan back in place, put in oil and re-installed the stater (removed for better access for RMS job. Reconnect the battery and go to start the Jeep. Now it is still on jack stands angled up at the front. I turn the key and wait for all the gauge lights to turn off. Turn the ignition and the engine fires right up but there is a hella loud metallic screech at the same time! Yikes. Immediately off. Try it again. Same thing.

I need help because I have no idea what it could be. It sounds like its coming from the flexplate/starter area. I took the starter off and the teeth look ok. Its not shimmed. I put the starter back on and this time, put the wheels back on and removed the jack stands. Try again. Same screech.

Any help on what to chase down would be greatly appreciated.

Is it at all possible that anything was left in the bottom of the bell housing when checking the flex plate bolts? Did you remove the inspection cover to take a look?

I removed the inspection cover and it is still off. I have accounted for the two 13 mm bolts and the 18 mm bolt. The other 18mm bolt cannot be removed unless I remove the exhaust.

Is the air conditioner system OFF when the start attempt is made? Was the fan belt removed during the work?

How long did the vehicle sit without running while the job was going on? (days? weeks?)? Sometimes bearings in engine accessories (alternators, water pumps, power steering, etc) will be fine if they are used every day or so...but if left unused for a while, will complain when brought back to life.

Just trying to gather information/clues.

Sound kinda like when you accidentally turn the ignition when the engine is running?
Makes me think something with the starter

@jordan96xj yes the jeep was on jack stands for about 2 weeks as I only worked on it when I had time. and the front was . higher than the rear so I figure oil and trans fluid drained back. Its on level ground as of today.

@884x4 Yeah but I put the old starter in first and thought that might the be issue but went and bout a new non-reman starter with the same result.

AC is off and belt was not removed. When I get my brother to start it, I am down by the flexplate and can hear the screech from that area.