Recently my Bosch Multitool had an attack of the "won't switch on's" mid job, and an alternative battery installed into it immediately heated to worrying levels. Today, I got to taking it apart in the hope that something would show as obviously wrong in such a way that I could 'unwrong' it and not have to replace it. A touch of the Repair Café philosophy: don't bin it, fix it. My next step, indeed, would have been to take it to the esteemed Stoke Climsland Repair Café.
The body is held together with Torx head screws, and some of them are quite deepset. But thanks to a very thoughtful Xmas present from Mr and Mrs Griffiths, I had the right size in my tool kit. Thanks are also due to the Bosch design team for their work in making the disassembly obvious. You can imagine (well, some of you might) my surprise and pleasure when I opened the casing and immediately saw the problem! A metallic foreign body wedged between the wires of the battery terminal. That would surely heat up the batteries! The only thing that puzzled me is how it got there? I assumed it had slipped through an opening in the tool's body ....
I removed it, and took the opportunity to clean out dust and grease bearings etc, then I reassembled everything. Having tested the tool as once again working (better than ever, I might add), I then took the object and tried to determine where it had entered. It turns out I could not fit it through any of the few grills and openings anywhere on the tool! Not any way at any angle.
Now I'm pretty certain that Bosch do not use old flat-headed brass slotted screws in their factories, and they certainly don't wedge them between battery terminals, so the most likely explanation is that it got in from something I did... I just don't know how. I will, however, now get even more pleasure from using the tool, knowing that I mended it.