Computer apparently dead on "93 STS

Hey: Please help.

Lost ALL the juice in the battery from a light left on.
(TOTALLY dead)

Jumped it off... no problem.

NOW: The computer will give readings (of some sort)
but only briefly.
Then: Nothing. Only 'dashes', as in ---.

The information in the center (just over the steering wheel)
is there; however, the temp reading IS NOT... only 'dashes'... as in ---.

Also, the readings to the right of the steering wheel (temp control, et al)
are DEAD. However, the light indicator for the rear window defrost STAYS on,
and the "AUTO" indicator STAYS on. They WILL not go off... no matter what I do.

I have disconnected the battery, let it set for a while and reconnected it.
NOTHING.

I went through the steps in the inst. manual: Still nothing.

The air does not work. The blinkers work. The lights work. The radio does not work. This is crazy.
\
Frustrated,
Will