I bought Pro 136 scanner at a second hand store and it did not have the three 1.5 volt back up batteries installed. Took it home, installed batteries plugged in the adapter, hooked up and antenna, and it worked.
For a week.
Turned it on one day to listen to marine band coms and it was bricked.
So I turned it off, pulled out the plug, and took out the batteries. Could not reset it.
Finally I unplugged it again, took out the batteries and figuring the radio was bricked from some electrostatic problem caused by the batteries, I bridged between the negative spring and the positive button in the battery compartment and let the radio sit overnight.
Next day I replaced the batteries, connected the power cord and re-connected the antenna and the radio worked normally.
If I don't plan on using this radio for awhile I disconnect everything and remove the batteries.