I'm trying to connect the gimbal to a serial port on my ardupilot flight controller. It's not working and I thought maybe updating the firmware might help.

2-axis gimbal. When I attempt to connect to the board with SimpleBGC_GUI_2_40 from the 8-bits download section, the program crashes. When I attempt to connect with SimpleBGC_GUI_2_71b9 from the 32-bit downloads section it does not crash. So I think it's a 32-bit gimbal. But I get errors:

The first is: "GUI vs board version mismatch. Firmware version: 0.53b4, GUI version 2.71b9_1. You should run matching GUI version, or upgrade firmware."

When I go to the firmware Upgrade tab, it says Device SN: unknown and Current version: 0.53b4. Click "CHECK FOR UPDATES"; different error:
"Error checking latest versions: java.lang.Exception: This device is not registered in the system:"

Click on the "Manual" tab, try to flash the file "SimpleBGC_2_40b8.hex". Says to close the FLASH jumper. Can't locate a it on the board. I don't see any jumper pins.
https://imgur.com/a/JCrK8EJ

I've read the manual, (it mentions a button instead of the flash jumpers. I don't see it). Installed the files from https://www.basecamelectronics.com/files/drivers/CP210x_Windows_Drivers_6_7_2.zip . Tried XLoader. ("upload failed")

I don't know what to try next. What should I do?