Typically once a receiver is bound to a transmitter, it keeps that bind info and won't need to be rebound to it. You may need to contact Spectrum support directly if this continues since it may be a hardware failure. You do need to power on the transmitter first before powering the receiver ( just in case you were not already doing that ). However I assume you have been using them previously, so that was just a cover it just in case.
Here is the user manual for the receiver just in case you need to refer to it for binding instructions as well as it has some troubleshooting info as well.. see
AR8360T Manual
A common issue when binding is having the transmitter and receiver actually too close together... so keep them far enough apart to avoid that. Why, if too close together the signal is overdriven and gets garbled. When binding, you must hold the bind button down long enough to initiate the bind. In addition, if you used a bind plug instead of the button, it must be removed before powering off and back on.
Updating firmware ... make sure you are using the latest programming software. You can download the latest here
Spectrum Programmer and instructions.
The firmware updater requires that you use their special USB cable to connect it to your computer. If you use an USB extension, it must be a data cable and not a power only type. I would also say to make certain your USB programming cable is plugged into the receiver in the proper orientation.
Any registration / account issues you will need to contact Spectrum directly. I read somewhere that Spectrum has two types of accounts and I'd assume you must be using the proper one for anything that requires that you log in first. I couldn't find the page where I read that again when I went looking for it.
BTW I think you will get faster response if you email them vs calling. Seems to me no one likes talking anymore, but you see everyone on the phone 