It could be the RTC, but unless did something to fry it, it probably isn’t. If you want to keep at it, there should be enough information in this thread to get it to work.
You can test to see if the RTC works by using the i2cget command, try something like i2cget -y 7 0x68 0. Look at the data sheet for the RTC if you want to understand more about how this works.
Also, the method described here doesn’t attempt to overwrite the default hwclock. You are supposed to run the script at boot to set the clock via timedatectl. The OS will have the wrong time until you run the script. You can set the script to run at boot with systemctl.