When this remote arrived it came with a watch style battery that needed to be inserted. The two page information sheet said "Insert a battery with the face marked + on top"
All well and good except the unit would not connect with my Canon HFM500. Also, it was nearly impossible to remove the battery because it kept hanging up on something inside.
The answer is to turn the remote control over so its back is showing on top, then insert the battery holder with the + showing on top. In short, the battery goes in contrary to what you expect and with the remote in its normal top up orientation the battery is in fact inserted with the + facing down. There is a diagram that shows this odd arrangement but it is very small and ambiguous. I can't help but think that the company must get a lot of returns because others made the same quite natural mistake.
As for the remote. It works perfectly with my Canon and would have got 5 stars had it not been for the very strange information sheet and the even odder engineering.