1994 Buick Roadmaster tail gate replacement

Interior problem
1994 Buick Roadmaster Two Wheel Drive Automatic 99,000 miles
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Hi,

I have an impacted tail gate on my 1994 Buick Roadmaster and have to replace it.
In a used part yard I have found a matching tail gate, however with the rear glass attached to it.
I am not able to remove the glass from the tail gate because the glass release switch is closed and a hook holds the glass locked in.
Mechanically, there is not any access to the hook to pry it open.
The only other way I see is to tie the tailgate wiring connectors to the battery and test all leads until the release switch opens.
Do you happen to have another idea how to separate the two ?

Thank you,

George