Back together again. Fired it up and it seems to work okay too. Yay!
I found a website where s guy shows you how to remove broken or stuck screws in eyeglasses. The extractor he used I have in my toolkit from I don't know where, maybe a tool show at a RC hobby meetup. Anyway, with a lot of 91% alcohol and soaking the busted one, the tool began to turn a bit back and forth and finally it came out. The replacements that come with the Battery Compartment fit in that spot too (I found I didn't need to remove the ones in back of the servo, just the three behind them.), but I had one in my junk pile of screws where I'm always taking stuff apart and keeping the screws and springs just in case.
Optician's screw extractor video:
Screw extractor tools for purchase:
Precision Screw Extractor Set / USA
If you keep the Loctited screws wet with 91% alcohol for several hours, you may not snap the head off like I did and not need the above extractors.
The rubber dampener was a bit tough to pull through the plastic floor pan and base and through the gimbal so I put a bit of water and soap on it. The old one definitely had a flat and even boiling it in water never made it round again. Might have gotten torn on removal.
I did find the toolkit from Amazon helped a lot in this job, along with the spring swivel portion to access the bottom Torx #6 screw on the MB. I used the Torx 6, 8, and 9 bits, along with the 2mm and 2.5mm hex bits. The kit has some plastic prying tools that are good for all the tiny connectors. The Vessel JIS screwdrivers 00 and 0 were used the most.
Toolkit here:
https://www.amazon.com/gp/product/B07HRLGK5M/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1
The plastic side panels ahead of the battery box as well as the plastic floor pan have some sticky tape that holds them. I cut some Scotch Double-Sided tape in 1/8" wide strips and applied them in their place.
I'd recommend a dab of Loctite Purple on the screws that go into metal and not the blue that is too strong for the small sizes. Loctite suggests the Blue for screws larger than 1/4" and all the
Inspire 2 ones are smaller than that and why it's possible to snap off one. Also, don't use Loctite around plastic threads as it will crack them (Lesson learned elsewhere.). There is a Loctite that is safe for plastics (Pricey too!) and Vibra-Tite sells it in their VC-series bottles. Given DJI uses so much of the blue stuff, you might not even need to use any as they bind up well as is.
I also used some Almond Colored GE Silicon from hardware store and swabbed that onto the two battery connections that had that stuff on them on the MB. Looks like factory did it too.
I haven't gotten the CE label off the side of the old battery case to stick it on the new one on the left side. I may try a heat gun later and see if I can peel it off.
Back to why the thing broke, the front part of the battery compartment is a pot aluminum casted piece which must have some prongs that go into the two plastic side pieces where the battery fits. I pulled the piece off under sheer strength and busted the pot metal part clear of the plastic sides. The remaining ot metal seems to act as staples to hold the two sides together. I may need to take it to the scroller saw and see if I can saw the stapled parts clear to get the side cases open.
Anyway, photos below show the screw extractor tip and removing the busted piece. The old deflated rubber dampener. Some of the dismantling of the battery box and the metal pieces in one end holding the sides together.
Whew! Glad that's done. Not bad if I didn't snap the screw, but it is time consuming first time dong it.