1) Install TeamWin recovery image to boot with (see and download your recovery image or in my case -installer-le-twrp-recovery-sur-samsung-galaxy-tab-a-9-7-sm-t550-sm-t555.132143/)For that case, you have to boot in Download mode. And then, you can use Heimdall on Linux and Odin3 on Windows (Windows Samsung USB drivers are necessary).Once installed, shutdown your device (or disconnect it).
I managed to root my phone and got Termux_CDC_ACM working under root, but for Anycubic S3 Mega it says serialDaemon:: Error: Couldn't find matching driver for usb device hex(dev.idVendor)='0x10c4', hex(dev.idProduct)='0xea60' !
The basic input/output system, which is a multi-purpose, stored, read-only memory device on the system board, can enable and disable integrated and peripheral components installed to the board. If the universal serial ports aren't working, the USB controller could be disabled. Turning on USB in the BIOS will restore function to the ports. If your business uses an older operating system in order to access outdated hardware or software, you can also configure the BIOS to enable the use of USB in operating systems that lack built-in plug-and-play support. 076b4e4f54