My wife and I both have Optimus S phones.
She upgraded to 2.3, I did not.
Her phone immediately stopped charging, started getting SD card not mounted messages, freezing up and generally just being a huge piece of junk.
Fast forward a few weeks, Sprint posted the 2.2 version on the website to roll back to.
I performed the downgrade on her phone to 2.2.
Her phone still refused to charge with the LG charger that the phone came with. (Works fine on mine though, and both phones are 2.2)
She continued to get SD card unmounted messages (although not nearly as often) even after the downgrade. My phone has never gotten that message and she never had it either before going to 2.3.
After much trial and error, I got rid of Sprint ID on her phone and switched her to launcher pro. The SD unmounted problem is now gone and her phone doesnt freeze anymore either.
She is currently using the charger for a Motorola Droid X, which is 850ma and I've found will charge her phone just fine.
My question is... what the heck did 2.3 do to her phone that even after going back to 2.2 it will no longer charge from the charger that it came with?!!?!?!
I have never seen a phone downgraded from the 2.3 update to 2.2 that maintains the charging and SD card issues. Are you sure it was actually downgraded to the 2.2 software?
It sounds to me like the software you flashed to it was corrupted or damaged somehow. I would recommend downloading the update.zip file again and performing the downgrade steps again, making sure you follow the actual steps 100%. You don't have to be on the 2.3 software to reflash the 2.2 software from the SD card.
Yes I am positive I actually downgraded her phone to 2.2.
I'm an IT systems engineer with many years of software development under my belt, I followed the instructions to a T and verified the version number afterwards.