I'm sorry to hear that you're experiencing issues!
Firstly, I'd like you to try updating the firmware on the device. This can be done by navigating System → Firmware → Update Firmware and either updating from the server, or downloading the firmware file from here. Please make sure, that the "Keep settings" option is unchecked, as updating from such an early firmware might cause the configuration files to corrupt.
If that does not help, I'd like you to describe the issue further. Does only the PWR LED lights up and nothing else happens?
When the device successfully boots, does it continue to function normally, or is there some abnormal behavior happening as well?
I'd also like you to generate a Troubleshoot file by navigating to System → Administration → Troubleshoot. The file can be attached to the original post and it will only be visible to Teltonika moderators.