I read through you 9 previous posts. Seems that except for the seasoning/burn-in, you have had success then a problem. Not sure where to start. As for the temperature rise to 300, your wood may have caught fire. That sometimes happens. Probes are sensitive to moisture. More than one person here and elsewhere has ruined a probe with water. So depending how often you have used your smoker the last 3 or 4 years you may need a new probe. Hard to tell.
As for the "H", this is from Auber:
For SMD-100, SYL-3615/SYL-2615, WS series plug-n-play controllers including WS-
1211GPH, WSD-1200GPH/1510GPH, AW-WST1510-W, WS-1510ELPM/1510DPM
-H-: This is an input error message. The possible reasons are: The sensor is not connected
correctly/firmly; the input setting is wrong type; or the sensor is bad. Please check your sensor
connection first. Simplest way to test is unplug/remove sensor, then plug in/install it back. If your
controller works properly before or you just reset your controller recently, please check sensor
input type parameter (if applicable). In addition, it is unlikely that both two probes go bad at same
time; to check whether your probe is bad or controller is bad, you can simply swap two probes in
different socket. If this problem comes with probe, this probe is bad; if this problem comes with
the socket, the controller is bad