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No matter what you do, you can't get the trimmer to turn on.
If your trimmer won't turn on, you may simply have a drained battery. Plug your trimmer in; the device should be fully charged in 10 hours according to the user manual.
Try charging a similar device with the same charging cord you used with the trimmer to verify that it functions properly. If the cord cannot charge your other device, it is most likely faulty and a new one should be purchased.
If the trimmer does not show any sign of life after a 10 hour charge, it is most likely that the battery itself needs to be replaced. Refer to the Battery Replacement Guide
If the trimmer does not respond to the on/off switch, then the power switch itself may need to be replaced. See this guide to replace the power switch.
Even with the power on, the blades appear to be stuck.
There could be too much hair/dirt between the blades or the blade may have become worn out over time. Check out the Blade Replacement Guide so you can clean or replace the blades.
The handle of the trimmer my have too much residue built up inside it, causing the motor to jam. You're going to want to see our guide so you can replace the handle.
The comb doesn't respond to the zoom lock adjustment ring
The Zoom Lock Precision Notch inside the wheel may be chipped or damaged and may need replacement. See this guide to replace the Zoom Lock Precision Notch.
If the comb itself does not stay in place or lock in properly, than it may be chipped or damaged and a new one must be purchased.