Hello, I am here to assist with your microwave problem.
The H98 error is related to the magnetron not receiving the proper voltage from the inverter. In short it could be a bad magnetron, or inverter board. Please refer servicing this unit to a tech, as the circuits can produce 3000 volts at high current. The capacitors will remain charged even with the power off and unplugged. Very lethal.
I hope you find this information useful, if so please accept my answer.