2 posts • Page 1 of 1
I suggest you download the user manuals of H501M and H501S from www.hubsan.com and check the spare part sections near the end of the manuals. If the spare part IDs of both ESC are the same, then it is the same part for both quads.
Regarding the firmware I have no idea. If anything, I think the H501M firmware should be more like that of the H501A.