Won't turn on or charge

Here's a few options: Soft Rest

- Hold down MODE + RESET for few seconds
- Press the Power button to turn on the device

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Hard Reset
(This will erase all of your data inside the device)

- Hold down MODE + RESET + POWER for few seconds
- Press the Power button to turn on the device

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Firmware Downgrade/Upgrade (2.9 > 2.8 > 2.9)
(This will erase all your data inside the device)

Software Downgrade/Upgrade

- Connect your Garmin Forerunner 305 to the computer
- Press the UP arrow button and hold while doing all the other steps below
- Press MODE + RESET for a moment (the computer will recognize the device)
- Dowload the Firmware from Garmin's website.
- Downgrade Firmware from 2.90 to 2.80. (You are still holding on that UP arrow button!)
- When the update is finished the Forerunner 305 should power on running the Firmware 2.80.
- Let go of the UP arrow button, disconnect the device from USB, connect it again and the computer should recognize it normally
- Update the Firmware to the current version.

Try hard reset.

Hold mode + start for ten seconds (device off beforehand). Keep holding then pulse push lap/reset button.

You get a screen asking to return to default settings. You will loose all your data, but device should work then

Had same issue... this worked for me:
1. Snap into charger base & plug into wall. Screen still blank. 2. Press Lap/reset, Mode, & Power buttons all three at the same time & hold for 3 seconds - unit will reset. Hopefully then you'll get the 'charging in progress' message.
(also make sure copper points/connectors on unit and charger base are clean).

Probably the battery. My battery lasts all of 20 seconds since i almost always have it plugged into car charger i guess i killed battery

Reset your unit by pressing the "Mode"(reset/lap) and "Power" buttons at the same time. afte it turns on run system updater on computer

This might just need a reset. To reset the Forerunner or Edge 205/305:

1. Connect the device to the computer using the USB cable
2. Press and hold the mode and reset (lap) buttons together for 10 seconds
3. Release and wait for 3 seconds
4. There should be some indication of battery charging (either Finished or In Process)
5. Power the device on while keeping it connected to the computer

In addition, please make sure that the device has the latest software version available by downloading and running the WebUpdater program. To update the software, please use the following link:
http://www.garmin.com/products/webupdater/

Same thing happened to mine. Put the unit in the cradle (just like you are going to recharge it) and press the reset and mode button at the same time for 3 seconds. This will "wake" the unit up.

I had the exact same problem and thought my beloved forerunner 305 had finally died. Try pressing the lap and mode keys simultaneously, and then power on. That may do a "soft reset." Worked for me.

To power the unit back on, press the "Mode" and "Reset" buttons at the same time. Let go of those two buttons, press the power button, and the unit will turn back on."

There is a hidden recessed button on the right side of the Garmin. Press this button and it should reset the unit and it should turn on immediately.