MBUS/FBUS programming adapter for Nokia 3310 and related

Intro

This adapter allows programming the OG Nokia 3310 or related (Nokia 3315, 3330, 3350, 3390, 3395 and probably others which use the same chassis). It solves two problems:

1. The battery needs to be connected (or power needs to be supplied through the battery terminals) or else the phone won't boot. If you want to substitute the battery you will have to faff around with connecting to the terminals and fooling the phone into thinking there's a real battery connected.
2. The programming pads aren't really accessible with the battery in place. This is pretty obvious as there's so little clearance so your options are pretty limited unless you have some kind of flat flex breakout cable (perhaps a future project?)

As you can see in the photos, this adapter solves both of those problems. The alternative is buying a shoe or shim or adapter for forensic equipment (usually these have an RJ45 connector on the end). There are also 3D printable shims which break both the programming pads and battery connections out, but then you run into problem 1 (unless you don't have a battery on hand).

Printing

Printing takes about an hour and 20 minutes on my Ender 3-V2 with conservative settings. Minimal finishing required. Printing with supports and 40% infill with PLA works fine.

Usage

You will need to install the battery into the adapter first, then install the adapter as you would the battery. I have tested on a number of phones and though it's a tight fit it does fit and remain secure, and can also be removed easily.

For the programming connector, the holes are designed as roughly 1.2mm in diameter. Since it is printed on its side these will probably be smaller in real life. However this means you can press-fit pogo pins or even use a DuPont connector pin or paperclip for contact with the PCB. The wires can then be routed out easily.