Update: I have found someone else found inside this Arduino Forum, as they were getting the same or at least identical issue.
Original Forum Post: HM-10 Bluetooth AT commands keep returning "ERROR"
It seems like, telling by the comments of the post, I may need to update the driver or board itself. Although I do not have an actual TTL to UART converter or even a Windows OS enabled computer of my own. All I have is Linux and a Raspberry Pi 4.
Does anyone know by chance that it’s possible to flash the AT-09/HM-10 through a Raspberry Pi 4 without TTL > UART Adapter? Is it possible to flash directly through the GPIO pins on the Raspberry Pi 4? If it’s not possible then I may need to buy an adapter myself, but I will look further more into hopefully finding another solution.