It’s way easier to resurrect a 3 year old post than it is to revive a drone dropped into salt water 3 years ago and written off by DJI no matter how much alcohol you bathe it in!
I'll rescind this thread, as this prior one seems to cover exactly what I am seeing:
https://mavicpilots.com/threads/mavic-4-pro-obstacle-avoidance-issues.152326/
I've not used the Mavic 4 however on the Mavic 2 Pro the only time I've had problems with false alarms on the collision sensors is around sunset time or there's harsh light angles. At night time it warns the avoidance system isn't working which...
The drone doesn't support faster microSD cards because it's limited by the hardware in the drone, there are several faster types of micro SD cards but the Mavic 4 doesn't have the hardware to use them. The older UHS-II spec offers faster speed...
Closing the loop here - I opted to purchase a refurbished RM500 Smart Controller via the "DJI Store" seller on eBay. $375, shipped to the US, took about two weeks to arrive.
Setup was easy, it recognized my M2ED with no issues, updated...