Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I am not sure that you can get it working by 5 am, if the Garmin is not recognized by your computer when connected to it after it is powered Off, and after you have loaded and started the Garmin Express program on the computer before connecting the turned-Off Garmin device.
So I suggest that you try that. And if Garmin Express can 'talk to' the device in this fashion, it may be able to overwrite a software corruption on the device, and get it working again. This is about all the chance you have of getting a Garmin device with this problem working again, at short notice.
It can of course be replaced, or sent to Garmin Repair, in the long run.
Tell me how it turns out, please. Thanks.