The second image with the higher colour depth is has a smaller file size then the other one with the lower colour depth, which is odd.
The big thing which stands out to me as dangerous is the lack of over-current protection. There should be a fuse or PTC resistor to protect against short circuits. You were wrong that it's not a concern. Whilst the likelihood of a short circuit may be low, the impact is big, since NiCd cells have a very low impedance and high short circuit current, which can cause wires to glow red hot and set fire to nearby flammable materials.
What's the case made out of? Ideally it should be flame retardant. In other words if you expose it to a flame, it shouldn't continue to burn, once the flame has been removed.