I stumbled into this problem while trying to install BusyBox. I have a OnePlus 7 pro with LineageOS 16 (rooted). But the solution might work for other devices as well.
Solution:
adb root
adb disable-verity
adb remountadb enable-verity
adb remountHave fun!
I saw a lot of similar mods for the older SynScan V3. Most of them connected the BT module to the serial port using an additional level shifter to convert levels back to TTL 3V3. 
Instead of using a second level shifter I did some research and determined the two TTL serial pins of the µC (pic18f85j10). Fortunately there were two vias next to those pins that could be used as tiny solder pads.
Also very helpful:
To avoid the risk of ripping the magnet wires I soldered thicker ones onto them and secured their transitions with epoxy again (see entry image).
The BT module has some exposed pin headers that I used to connect the wiring to. To avoid any short circuits I put some heat shrink tubing around.
Setup successfully testet with SkySafari 5 Plus for Android.
That’s all Folks
Please note, that the USB power pads of a Pi Zero without WiFi will not match.
For the lite version you can skip all steps involving ENC28J60.
Download and print my 3D design:
Ultimate:
https://pinshape.com/items/39162-3d-printed-pi-zero-ultimate-housing
Lite (USB only):
https://pinshape.com/3d-printed-object/6321-pi-zero-lite-housing
Solder the wires to the pogo pins and don’t forget to reduce the bottom diameter of two pins to fit into the holes for the USB data lines.
Yes, everything has a real tight fit!
VCC(3.3V) -> 3V3 (Pin 1) GND -> GND (Pin 6) SI -> MOSI (Pin 19) SO -> MISO (Pin 21) INT/IRQ -> GPIO25 (Pin 22) SCK -> SCKL (Pin 23) CS -> CE0 (Pin 24)
To make good contact you should put some solder into the pin header holes of your PI’s SPI IOs and power supply.
To have good performance, I used the Raspbian stretch lite: https://www.raspberrypi.org/downloads/raspbian/
After burning the image to a micro SD following files on the boot partition have to be adapted:
Add those two lines to the bottom of config.txt:
dtoverlay=dwc2 dtoverlay=enc28j60
Add this after rootwait to cmdline.txt:
modules-load=dwc2,g_ether
Enable SSH by placing an empty file named ssh to the boot partition.
Boot up and ssh into your pi zero:
ssh pi@raspberrypi.local
If you have a Windows machine, you need to install Bonjour to resolve the *.local suffix. Mac and Linux normally can handle this.
Enable SPI via raspi-config -> Interfacing Options
Reboot and enjoy real (but slow) Ethernet and Ethernet over USB!
Experiencing a boot loop? Try it again with an additional micro USB cable. It seems your computer doesn’t provide enough current.
I created this induction heater based on this schematic from http://www.rmcybernetics.com:
One of the most important things would be the BOM I used. On the internet you’ll find a lot of suggestions. Due to the fact, that I want to use this heater as an induction furnace, I modified some parts so that the whole system can handle more power.
I have two 24VDC/12,5A SMPSs in parallel. These bring sufficient power for heating medium pieces of iron until they’re glowing. For an induction furnace I will need more power to heat my graphite crucible to at least 700°C for melting aluminum (melts at 660,4°C).
Here I offer you the chance to have a look at my progress of creation. I hope this helps you to avoid some unnecessary mistakes.
Because my breadboard went on fire I had to change my prototyping platform. Yes, beyond the driving circuit there is a lot of power!
But hey… its working! 😀
Fun fact: This construction has a clever safety feature! If the FETs get too hot (yes, really hot), the attached drain wires snap off.
