Going right back to taws, you are at the mercy of 1) battery condition (main battery or batteries and internal backup battery); 2) adapter condition; and 3) PowerBook condition.
Some or all have worked during your demonstrations, so there is no cause for despair. The internal (secondary, ie rechargeable) battery does not recharge before the main battery in the right-hand bay has reached nearly full terminal voltage (about 10.5+VDC), not full charge. After a long rest without the adapter connected, that can take up to 48hr. The PB 500s have inappropriately-named smart batteries that may need special techniques to kick them back into sentience (not intelligence).
The PB itself may respond to the brightness/contrast controls soon, but it has already demonstrated that it has life. You need to get on top of the power supply before any testing of the PB can be rewarding. As long as the main battery is not dead-shorted (which will show as extreme heat during charge), the PB will function with a battery in and the adapter connected, no matter how ineffectual the battery is otherwise.
Trawl these forums for more detail about the main and backup batteries and the adapter. You have inspected/cleaned the main battery terminals?
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Some or all have worked during your demonstrations, so there is no cause for despair. The internal (secondary, ie rechargeable) battery does not recharge before the main battery in the right-hand bay has reached nearly full terminal voltage (about 10.5+VDC), not full charge. After a long rest without the adapter connected, that can take up to 48hr. The PB 500s have inappropriately-named smart batteries that may need special techniques to kick them back into sentience (not intelligence).
The PB itself may respond to the brightness/contrast controls soon, but it has already demonstrated that it has life. You need to get on top of the power supply before any testing of the PB can be rewarding. As long as the main battery is not dead-shorted (which will show as extreme heat during charge), the PB will function with a battery in and the adapter connected, no matter how ineffectual the battery is otherwise.
Trawl these forums for more detail about the main and backup batteries and the adapter. You have inspected/cleaned the main battery terminals?
de