Why does my FMOUSE M333 mouse only work when plugged in and show no lights when switched to ON?
Based on the symptoms you described, it is highly likely that the internal battery is either completely depleted or faulty. According to the FMOUSE…
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FMOUSE M333 Silent Plus Wireless Mouse Instruction Manual — questions & answers
Read product questions and troubleshooting answers linked to FMOUSE M333 Silent Plus Wireless Mouse Instruction Manual.