Thunder 1220 charger issues.

My thunder 1220 charger screen goes dim after about a minute on the charger. It doesn't discharge at all. When it does charge it doesn't show cell voltage. I read a review that someone had the same problem.

I'm looking to either try and fix it or replace it with something comparable, maybe 200w even.

Your screen name "hits the nail on the head".
There's been a number of Thunder 1220's that have died that have been mentioned here. Mine only lasted two years, but that is longer than the Hyperion 1440 that I had before it.
I suppose you could try and repair it, but I'm not aware of anybody here who has tried. Perhaps you could add a cheap Ebay Volt/Amp mini-meter in an effort to get more service out of it.
Personally, after I went thru three of the "toy chargers" and due to there are currently no balance chargers over 10S, I finally wised up and started bulk charging my 12S and 14S LiPoly w/ Mean Well HLG series power supplies. That was a couple of years ago and they(I have two of them) are still going strong.
I'm no expert on "round cells", but if you added a BMS, you would have lot's of charger options, right?