"To determine if your Nuvi's switch is broken with no other issues, please confirm the following:
1. Pressing the on/off switch has no effect and the switch feels mushy
when pressed - no soft click.
2. The unit powers up and operates normally when using the car adapter
or USB adapter and can be turned off by pressing the reset button.
If the above conditions appear to be the symptoms of your Nuvi 350,
then most likely, the on/off switch has broken off from the main printed circuit board. use these guides to help
It's very unlikely that the switch itself is bad. The life cycle of this switch is 250,000 cycles. For example, if you pressed it 20 times per day for an entire year, that would add up to 7,300 presses per year. Divide 250,000 cycles by 7,300 and it would take 34.25 years before the switch would fail. No doubt the switch will outlive the Nuvi itself.
Taking the Nuvi apart itself requires the right tools. The internal flex cables for the antenna, touch screen and LCD screen are delicate and can be torn easily if you're not careful. The antenna flex cable runs through the swivel antena shaft and is very delicate.
You will need a surface mount desoldering/soldering station with illuminated magnifier. A standard soldering iron is far too big to solder the leads and will overheat the solder pads, lifting them off the board. All work should also be performed with proper grounding to eliminate static charge issues. . use these guides to help be blessed.."