i am lost...please help

my pap has a 98 silverado and his cassette player quit working. so, i took it out to replace with another delco unit. no problem right... 15 min fix right...
wrong........ we snapped the dash back on and he started the truck to leave and the air cond. button wouldn't light up and no a/c. along with the zone. adjustment knob. the fan switch still works fine though. what did i do?
he swears that it worked fine before i switched the radio's. possible reset of the ecm or a bad spot in the heater control unit in the dash? please help!!!

my pap has a 98 silverado and his cassette player quit working. so, i took it out to replace with another delco unit. no problem right... 15 min fix right...
wrong........ we snapped the dash back on and he started the truck to leave and the air cond. button wouldn't light up and no a/c. along with the zone. adjustment knob. the fan switch still works fine though. what did i do?
he swears that it worked fine before i switched the radio's. possible reset of the ecm or a bad spot in the heater control unit in the dash? please help!!!

whenever doing a repair like this remove the battery negetive terminal...

with a meter check all fuses.......................