Monsoon E 20 /E30 codes, stumped here

[Maryland Bandit]

Hey all, Sorry my fist post has to be a problem, but you guys definatly know these 4th gen cars well.
Just purchased a 1999 30th anniversary Trans Am, beautifull car. Have a 1979 Y84 S/E as well.

Issue is with the CD player(s) The head unit is a stock GM monsoon unit, as well as the stock 12 disc changer in the trunk area.
The radio works perfect. When inserting a CD it clicks and after 10 seconds, ejects it with a code E20
Tried the changer, its searched all 12 trays then displayed E30.
Rather then spend 200 to have the head end fixed, I bought a refurb unit from a decient ebay vendor. This one even has a ipod jack in the front. He tested it before shipping, worked fine.
Last night, installed the ebay unit, 15 minutes, piece of cake install.
Set the stations, let it warm up, set the clock.
Installed a store bought new CD, click, click, small cd icon displays then E20 code and the radio comes on.
Ooook, tried the changer. Searched all 12 traysm, FOUND the tray the disc was in, displayed track and time, then E30 code. Ipod jack works great, crystal clear.
Emailed the ebay vendor, he's stumped, it worked fine on his bench before shipping. Offered a refund , but I really like the ipod jack since thats where all the tunes are anyway.
Going over the service records with this car, I saw where the original radio was replaced under warranty back in 2001.
So, am I stuck with a wired up dead changer in the trunk and a dead head unit that will play a radio and ipod ,but hates CD's ? Thanks in advance for any answers, appreciate it.

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Thanks for info