I'd say at least to pull and reseat the two connectors on the sound board and also spin the two potentiometers back and forth some. I don't think the latter will do it since you've lost both sound and speech. Recapping this board tends to fix most ills.

From the Pinwiki site:

Blink Meaning
First "flicker" The processor has found the program code in ROM, and has begun to configure the board.
First Blink The 128 bytes of system RAM (either within the 6802, or external in the 6810 if configured with a 6808) have tested good.
Second Blink The 6821 PIA at U7 (which controls speech) has passed test.
Third Blink The 6821 PIA at U11 (which interfaces with the AY3-8912 and fields sound codes from the MPU) has passed test.
Fourth Blink Communication with the AY3-8912 has passed. Note that the PIA at U11 must be communicating correctly with the AY3-8912 for this test to pass. If there is no fourth blink, first swap a known good 6821 into U11.
Fifth Blink The TMS5200 Speech Chip has passed testing.

It has been mentioned that the pins on these chips can become oxidized (these boards are old!). The sockets themselves can also be a problem. You can try to carefully remove the chips, look at the legs for discoloration, try to clean (scotchbrite) and very carefully reseat.

Review the pinwiki page. http://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Squawk_.26_Talk_Sound_Board_Troubleshooting