Chrysler Repair: 98 T&C Electrical issues, slide pots, calibration test

Question
We have a '98 T&C LXi that we started having electrical problems with about a week ago, including: radio cutting in and out; odometer & gear display flashing; a buzzing sound coming from the area near the fuse box under the dash; rear interior lights coming on all by themselves; the rear a/c, rear washer/wiper lights blinking. The clock has never kept the correct time overnight.  It keeps the time during the day, even when you turn it off, but loses the setting overnight.  We took it to a garage and they 'resolved' it by putting a new battery in it. The van starts now, and the buzzing has stopped, but the radio still doesn't keep the correct time and two of the rear (a/c, wiper) lights are blinking, two are completely out and won't come on when you push them.  We tried the 'recycle' thing with the blower/holding the buttons for 5 seconds and it hasn't worked yet. Someone told me to check the grounds, but I don't know where they are to check them.  Can you give me any solid advice?  Thank you!!

Answer
radio  might be a loss of power to the radio  or the radio itself.

CALIBRATION/DIAGNOSTICS TEST ENTRY
TO INITIATE TESTS:
Set Blower motor ON HIGH
Set Mode position to Panel
Open all A/C outlets
Set Temperature to Cold (Both slide pots if equipped)
Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until all LED's light)
RESULTS:
All LED's will turn on for 5 Seconds
Calibration Test is running when REAR WIPER and INTERMITTENT are alternately flashing. Cooldown test is running if A/C and RECIRC are alternately flashing.
Acceptable results is REAR WIPER LED is the only LED flashing. Push Rear Wiper to exit.
After all tests have passed, Calibration Diagnostics and Cooldown can be run separately.