If there was a loud pop, it sounds mechanical. Are there any leaks? Have you checked the fluid level? When you start out in first, is there any slipping?
First and reverse work off the same clutch pack. There is a low/reverse band in the transmission which may have come apart causing this as well. If you look at the pic below, it shows a list of mechanical issues related to a no reverse. Everything there requires taking the transmission apart. So here is what I suggest:
The first thing I would do would include a few basics. Is the fluid clean and full and are there any leaks? If that checks good, then I would recommend having the can-bus scanned. CAN stands for controller area network. Basically, all the different computers/modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module which stores them. In this case, a transmission control module or powertrain control module may have helpful codes.
Here is a video showing how it's done:
Let me know what is found or if you have other questions.
Saturday, July 10th, 2021 AT 9:55 PM