Electrostatic discharge (ESD) can absolutely damage electronics - this video (you can download a pdf of slides) by Texas Instruments (experts and reputable source) details the issue -
TI Precision Labs - Op Amps: Electrostatic Discharge (ESD) | TI.com Video. BUT, a lot has to do with the individual design - how good were the components that were used, and how many times has the circuit been subjected to the ESD. Subject op-amps to repeated ESD events and eventually they can fail.
To the OP, using an anti-static brush incorrectly is an bad as not using it all. Assuming you are using the common Audioquest carbon brush, for that to really work you need to ground yourself (touch any metal that has an electrical ground) to discharge any static you and/or the record have to ground. You did not state - but is the tonearm grounded to the phono-amp? If you have a multi-meter, you can easily measure resistance between all components (metal casing) and the wall outlet ground (power source) to verify all are grounded.
To the OP, using an anti-static brush incorrectly is an bad as not using it all. Assuming you are using the common Audioquest carbon brush, for that to really work you need to ground yourself (touch any metal that has an electrical ground) to discharge any static you and/or the record have to ground. You did not state - but is the tonearm grounded to the phono-amp? If you have a multi-meter, you can easily measure resistance between all components (metal casing) and the wall outlet ground (power source) to verify all are grounded.