2Sondad

Hi, 2004 Bullfrog Spa owner here, with a Balboa BF01 (P/N 52847-03, now 59003) circuit board. The spa had not been used in a few years, so it was drained and refilled. After turning it on, the panel flashes 112, 03, then 240. Then error code Snb. I purchased 2 new sensors, and I replaced both A and B. I turned it on and I am still getting the Snb error code. However, after a few minutes, it also flashed SF, and then ran for 5 minutes or so. Then stopped and it continuously shows Snb. Thoughts on my next step?