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I need replace Back Rear GLASS in Samsung Galaxy Watch SM-R800 46mm. I am looking for detailed guide for replacement. Thank you for your help.

@aileenmk review step 4 and 5 of this teardown Samsung Galaxy Watch Teardown

I did it with mine. It’s pretty straight forward. After removing the back plat the heart rat monitor is easy to access and remove. Heat the glass from the outside for easy removal. Although be cautious as the small frame for the heart rate monitor can warp (this is what happened to me). Remove the old tape then place the new tape and glass (kinda like tempered glass screen protector) making sure that all the holes line up correctly.