Hello & Welcome to Just Answer,
Sorry to hear of any issue you are having with your device.
To help you with this issue, may I ask:
1) WHEN was the device last used SUCCESSFULLY?
2) The AGE of the device?
3) WHEN this issue first began?
OK - first, I see this is "duplicate" of an earlier question, and I will try to have that earlier question closed - so you won't be charged for it.
Please try to keep all replies on this question thread.
Now that other question will be closed, may I ask :
1) for HOW LONG you had this unit connected to power - before trying to power it up?
2) What power source are you connecting to?
I see your request for a "Premium Service" (phone call), but I'm not near a phone right now to be able to do a call. But another expert may respond to your request at any time - before I can reach a phone.
What AC power adapter was used (was it a Garmin Adapter)?
And did you try to power ON the device WHEN connected to that adapter AND when it was disconnected?
OK - that fine. I'm just trying to find out if the adapter WAS/IS working - and that the device will take a charge (after sitting for six months).
So may I ask WHERE and HOW the device was stored for that six-month period?
I ask because the (tiny) battery in the device MAY have been weakened over that period of time - especially if exposed to extreme temperatures.
OK - that sounds good.
So may I ask if you still have the USB cable handy - for connecting the device to the computer?
I only ask so that we can try an alternate cable and charging power source AND to see if the device is "seen" by the computer (once connected and allowed to charge for a while).
NOTE: When connected to a computer, the internal battery will charge much more slowly. And with some "portable" computers (laptop), it may not charge at all.
So what type of computer was it attached to - and for how long?
If so, is it a desktop or laptop computer?
OK - was the laptop turned ON for those 8 hours?
And was it NOT in a "power saving" mode?
I only ask because some (many) laptop computer turn OFF the power to the USB ports - when the computer is not in use, or a USB port has not had any activity for a period of time.
OK - I'm not familiar with the different power settings on this particular laptop, so let me make a recommendation for what to do now - to see if you can get the device to power up.
1) Connect the device to a KNOWN GOOD power source, and leave it connected (to attempt to charge the battery) for TWO HOURS.
This power source could be your AC adapter (if you TEST it and it powers a DIFFERENT device), or it could be the vehicle power adapter.
2) After that TWO hours, disconnect the device and try to power on again, by pushing and HOLDING the power button (usually 30-45 seconds should be enough).
Please give that a try and let me know your results.