Please also check the predecessor of Toshiba T1200XE: Toshiba T1000XE.
To change BIOS settings, you need a special SETUP1.EXE tool.
Power Supply Board
Backlight Inverter Board
It is possible to replace all the batteries with modern cells, for example here are AA rechargeable batteries place in the original casing by the previous owner of the machine:
The original T1200XE contained 20MB JVC HDD, which configuration was hard coded in BIOS. This HDD comes from T1200XE-40 version, that was upgraded to 40MB JDE2850P30-2 HDD. I noticed two versions of the BIOS (written on EPROM). Version 083A seems to support 20MB drive and version 083B supports 40MB drive.
The drive can be replaced with a modern Compact Flash to IDE adapter. I have not tried to make it boot, it probably requires installation of a solution like ANYDRIVE.
Floppy Disk Drive
2MB Matsushita ZA0856P01 EME263-TL. It is a really problematic drive with its rubber belt propelling the disk rotation. The belt dissolves with time. It can be replaced with a new belt, I fortunately had some belt that just fit, but I don’t know the exact parameters needed.
I am not sure if this bag is 100% accurate for this model, but it is Toshiba, it is retro and works well and look great here.