TPMS won't pair up

[gv550]

I've been using the Garmin TPMS sensors on both wheels for 2 years with my 395LM. The system works well and the batteries last 25,000 miles or so. I recently used my 395 in my truck for a 2000 mile trip, the 'TPMS wheel sensor is not connected' warning was showing the whole trip because the bike was way out of range and I just ignored it. I now have the 395 back on the bike and the 'not connected' warnings are still there and there is no readings for tire pressure. I replaced the batteries, then unpaired both sensors, and now neither sensor will pair to the GPS. What do I need to do to pair them again, surely both sensors haven't failed at the same time?