you probably already know most of this, but i'll recount for anyone just casualty browsing, and for the sake of prosperity.
in a nutshell the CPS2 has decryption keys in the form of a 64bit cypher stored in NVRAM that is used in 4 rounds of block decryption to obtain the final data.
the keys were figured out back in 2001 when unencrypted data was eventually obtained by sniffing and extracting the data out of a system after it had been decrypted and then processed outside to obtain the original decrypted data.
the decryption key is lost when the battery is removed/dies and the key data the decryption is now zeroed out... the data can't be decrypted cause the key to decrypt the data doesn't match anymore.
by about 2014... 15...16... ish? (somewhere around there i seem to remember) products designed to inject data into the decryption system started becoming more common on the market. the infinikey/openkey essentially is an atmel microcontroller that sits and listens for the call for the keydata... it then takes the (now publicly known) decryption key data, and feeds it to the decryption subsystem directly when the call is made. regardless of what the data currently contained in NVRAM, (zeroes or even a different games data). that basically all it does. the infinikey/openkey supplies the data key and the system operates as normal. this allowed people to resurrect their dead boards... and even convert the board itself, to other CPS2 games by swapping out the roms.
i have not looked much into this, but i think most... if not all cps2 games now... have "keyless" or "decrypted" romsets existing somewhere. you can just swap out the existing key encrypted rom data with data that is encrypted with a "zeroed" out keydata, so it works with a stock system with no modifications other than the rom data.
I have had no CPS2 games for a long long time, we got rid of them before the proverbial dookie hit the fan with them, but at that time things were quite far along in the decryption realm, and it was only a matter of time before it didn't matter anymore... which we, as a business, unfortunatly did not have. Having a machine down meant losing money... not in the "Not bringing in quarters" sense, but in a, "we have to pay 2 employees a special trip to go to a location to take it out" kind of sense.
i mean, there is nothing wrong with going the way it is and just fixing your data corruption, it does work as designed. (other than it may not be visually appealing or stock looking)
there is also nothing wrong with going back stock by programing new keydata into the NVRAM and going bone stock. (other than suiciding again)
and i don't see anything wrong with reprogramming decrypted data (IE zero keydata encrypted data) into the roms. (other than you may or maynot be able to do it in your specific case... and it's not "legit stock")
honestly, it should really depend on what you are looking to achieve. are you restoring an original game to new condition for a collector? are you fixing a mall foodcourt basher? what you ultimately decide to do could entirely depend on your abilities and access to equipment to do it.
anyway... there's the rub. saving machines from the scrap pile is always a noble effort.