SM-T800 Project
Modifying a SM-T800 for SkySafari 7 Pro

When I was in university from '14 to '18, I had a Samsung SM-T800 tablet that I used for reading textbook PDFs on. It is a 10.5" arm-based tablet with a AMOLED screen. It died back in '17 and it has been in my computer cupboard since, untouched. 

It also runs an old version of Android- much too old. It runs 4.4.4 and the most recent offically supported version of Android on this tablet is 6.0.1, and SkySafari 7 Pro requires Android 10 and up. 

With the advent of the PiFinder and my desire to continue sketching, sometimes I want to find objects with the PiFinder that are not in the internal catalogs. This is where SkySafari 7 Pro comes in.  It can connect to the PiFinder on my telescopes, and tell me where to point the telescope to find DSOs (Deep Space Objects). 

I did not want to go out and buy a new tablet if I already had a dead one with a super nice AMOLED screen in the cupboard. I knew the charging port was the problem but did not really want to fix it until I had a need for it. Well, now I do. 

SkySafari 7 Pro requires Android 10 or up. Cyanogenmod 11 was installed on the tablet, which is based on Android 4.4.4 KitKat. Old. Samsung stopped at 6.0.1 with this tablet. So, flashing the newest stock ROM was not an option. Flashing LineageOS (itself a descent of Cyanogenmod) with a more recent version of Android baked in was the prudent course of action. LineageOS 17.1 is based on Android 10. Still old, but recent enough that I can run SkySafari 7 Pro. 

So, what I did was: 

1. Disassemble the SM-T800 by removing the back, the screws securing the charging port, and the ribbin cable for the charging port. 

2. Replace the charging port with a $8 replacement part. 

3. Reassemble the SM-T800.

Then, the fun part; 

1. Flash the latest firmware with the 6.0.1 bootloader to the tablet with ODIN (tablet in download mode)

This also wiped out TWRP. Oops. 

2. Flash TWRP 3.6.2.90 using ODIN (tablet in download mode)

3. Reboot to TWRP. From there, I  sideloaded the zip fo LineageOS 17.1 which is based on Android 10 onto the device, then I wiped the device and flashed LineageOS 17.1. 

4. Flashed Gapps Lite 

5. Rebooted. Installed SkySafari Pro 7. 

It's not hard to take apart a tablet like this one. It's a matter of popping off the back cover with a guitar pick. Once the back was off, I replaced the charging port with a $8 replacement. 

It is much better than spending $$$$$$ on a new tablet. I'm relieved that SkySafari knows to disable the lighted hardware buttons on my tablet when it is started although I can modify this setting in lineageOS options.

So far, SkySafari 7 Pro runs fine. The OS itself is a bit laggy, to be expected when a modern version of Android is run on 11+ year old hardware. However, the AMOLED screen makes reading ebooks, watching Netflix or streaming movies/TV shows over the LAN via VLC a treat for the eyes. 

This project was well worth $8 and a few hours of my time.