I'm glad I came across this thread. Makes me feel better that I'm not the only one. I've had my Lowrance 3G since 2018 and last Sunday in the thick fog it decided to stop transmitting. The dome is detected and can power on/off, transmit, standby but nothing on the screen except the little dot in the middle. I took off the dome and verified the unit is turning.
Lowrance Support told me I could try to get it repaired at Stryker Electronics in Port Hardy or they can replace it with a newer Halo unit for $1045 USD but they are back ordered till December. Seems like a good price, but I'm not sure I want to go with Lowrance again.