There are lots of reports on here regarding this issue. Some users have reported that they have been offered a free fix from a repair centre.
Don't think I'd have ignored the warning and restarted the phone, but I understand you may have had no choice.
Saying that, I don't know of any official Samsung OTA update that comes with that specific warning. Surely, the update would not have been issued if that was the case, so can only assume you've downloaded a 3rd party firmware file? If you have, then community guidelines prevent me from offering any more advice.
