Make sure you don't have a short circuit somewhere (soldering tin or small pieces of cut wires)
Remove all batteries (backup battery included), press "ON" about ten times and wait a few minutes. Put the batteries back in and try to start the calculator again.
If this doesn't work, try this: Take out all batteries (backup battery too) and make a short circuit: connect P2 and P3 with a wire and wait a few seconds, remove the wire, put the batteries back in and turn the calculator on again.
+--------------------------------------------------+ | +----+ +----+ | | | P1 | | P3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-----------+ | | | | | | | | | | | | | | | MemUnit | | | | | | P2 | | | | P4 | | | +----+ +-----------+ +----+ | +--------------------------------------------------+
If your calculator still doesn't work, try to restore the
original configuration: remove the 8pF cap and put back the old
C11
If this is working you may try to use 15pF instead of 8pF (if you
don't have a 15pF capacitor connect two 8pF capacitors in
parallel) this is more stable but makes the TI "only" about 1.8
times as fast as with the original C11.
Note: Please don't e-mail me if something goes wrong, I'd like to help you, but I'm quite busy and I couldn't do anything else than telling you what I have already written on this page, sorry.