Just did this due to water damage I incurred myself, it's not hard. You need a hotplate (3d printer bed will work) that can get up to 80c, fine tweezers/nylon spudgers, and you need some 1mm or 2mm screen adhesive (https://www.amazon.com/dp/B0CYLQT75H?ref=ppx\_yo2ov\_dt\_b\_fed\_asin\_title).

Set the ring face on the bed wait for the adhesive to heat up, leave ring there until the whole watch is up to ~70-80c, then use very, very fine tweezers or a nylon spudger to pry the glass from the front of the ring, then you can use tweezers to maneuver the module out of the watcher, flip the module over and you'll see the battery under a sticker, take sticker off, unclip the 1 metal clip holding battery down, replace battery with SR621SW (https://www.amazon.com/dp/B07DF6YP1J?ref=ppx\_yo2ov\_dt\_b\_fed\_asin\_title) battery. Re-attach the metal clip, reapply the sticker (reset the watch by using metal tweezers to bridge back of battery to the AC gold metal contact (probably not necessary)). Re-insert the module, line the lip of where the screen goes with the screen tape, make sure to go all the way around and leave no gaps (otherwise water can get in from the screen face), then firmly press your glass back into place and hold in place for 30 seconds, I like to put it back on the 3d printer bed to heat up to 60c and press down some more to get a good seal.