Perhaps the games got damaged due to your cleaning process? How exactly are you cleaning them? It seems strange to have so many carts stop working all at once…
The safest and easiest way to clean game contacts is with CRC Contact Cleaner IMO. It won't harm plastics and does not remove the protective gold plating of contacts either. It's only $5 for an 11 ounce can too.
For severely corroded contacts then Brasso Metal Polish might get your dead games working. Use only as a last resort though as Brasso is highly abrasive and will remove gold plating. I've resurrected many games with Brasso though and it's a valuable tool if used sparingly and carefully.
I find the console that gives me the most trouble is the Colecovision. It's the only system that I have a stack of "dead" games for. Zaxxon is an especially troublesome cart; there’s a high chance for me that copies of the cart won't work or they have graphic or sound glitches.