I've got an ageing Nokia N70 which recently has had trouble with the camera not turning on when I slide lens cover down.  I rarely use the camera so this hasn't been important until this morning....

Let's fix it 

I did a quick Google and it seems many people have experienced problems with the camera in the N70 either stopping working, or working intermittently (starts then stops while the cover is open). Nobody seemed to be able to offer solutions that always solve the problem.

I got down to business this morning to see if I could fix the problem. I had noticed that back cover hadn't been fitting well for some time and had put it down to wear - it's an old phone now and is well worn. It seems that just squeezing the cover seemed to do the trick (activates the camera switch fully), and the camera went back to flaky mode the moment I released.

When I looked more closely I found an alarming problem:  The battery.... bulging

This is the original Nokia BL-5C battery that came with the phone in the box when I bought it and not a fake / third party battery.

If you have an N70 with a flaky camera, or a phone where the battery cover doesn't seem to fit properly, I would advise you examine the battery carefully.

Lithium battery dangers

There have been a number of reports of batteries in laptops, iPods, mobile phones and other portable devices exploding - all of these contain Lithium batteries (normally Lithium-ion or Lithium-Polymer). Although rare, Lithium batteries can explode if they rupture: Lithium will easily ignite in the air and reacts strongly with water (or even just moisture). If a failure occurs in the battery, it can result in the energy in the battery being turned into considerable heat which can kick off the reaction.

Chargers have to be very carefully designed and there are a number of safety features including time limits, fuses (current limits) and temperature monitoring. While designing chargers for Lithium batteries, I have never come across any safety mechanisms for the physical integrity of the battery.

Of course, provided they aren't in my pocket at the time, exploding Lithium batteries can be entertaining.