MIB1 coding for 47: 22000000AAAAAA0000
MIB2 coding for 47: 12000000AAAAAA0000
If I do have to get the MIB2 amp, I assume it is as per other retrofit threads, buy a used amp, get CP on the amp removed, good to go?
So many have been able to use the MIB1 amp by doing the coding changes you performed. If it was me, I would not look at the MIB1 amp as the problem and throw more money into a MIB2 amp. The volume bar staying solid would lead me to believe it is the headunit. You could also verify by coding for non-fender and then throwing some spade lugs on the output pins for speakers and throw a speaker across. However, that likely would just waste time, but beats wasting time and money.