First thing to do is unplug your radio, powering up/down and trickle charge will just add to the ability of the caps to ruin the circuit boards.
Possible Repair:
There appears to be at least one guy that is repairing these stereos. As of 2020/06/18. Challenge: all in Japan.
http://grfblog.seesaa.net/article/470088635.html
http://grfblog.seesaa.net/article/475069361.html
http://www.eonet.ne.jp/~grfnsx/
You might try
https://www.unitedradio.com/automotive-electronics/repair-remanufacturing/ Challenge: good luck.
Alternatives:
OEM radios come up from time to time that are still working. They, too, will eventually fail, but might work for a few more years and kick the can down the road. This is a legitimate strategy.
A remote radio like a DMHD1000 which are probably +20 years old, but the are still on eBay and
Amazon. I've picked them up for as low as $20 and they are very cool. But without a working radio they would also need a hidden radio to decode the RF and power up the Bose amps (see aliExpress for $10 items that would work just fine).
There is another NSXer who just installed a plastic plate where the OEM radio would go and found a small stereo system that could be installed within the OEM console. Worked well, cost effective, and looked OK.
You can do a hardware hack like
Willmans, about $1500 currently. Many satisfied customers. It works well, but doesn't use the buttons as it expected and, to me, doesn't really look & feel like OEM. Willman doesn't repair stereo's anymore, he considers it impossible and/or offers an extremely low chance of success.
I am working, helping mostly, on a full hardware radio emulator that uses the OEM display and controls. But it is an very challenging project to say the least. If you are looking to sell your unit, I would be interested as I need R&D cores...this is a retirement project to keep my mind from turning into oatmeal.
Do/not:
Do unplug your stereo. Store in a cool place if you can.
I recommend not damaging or cutting your OEM console bezel/frame. Keep it intact, they will go NLA soon enough and they will be worth a small fortune, because right now they are worth a slightly smaller fortune.
If you must put in an aftermarket stereo, buy an aftermarket console (not affiliated at all, but EuroBoutique might be able to help). An aluminum CNC replacement would be awesome as, I'm sure, as well as the price.
