The battery and charger inputs have fuses. A short circuit will blow the fuse. Also, laptops and notebooks run on lithium batteries and have complex monitoring of power consumption from the battery. This is easily achieved with a shunt resistor (a low value series resistor that is used to measure current) which is hooked into the battery management circuit. It is pure marketing hype to include a mention of short circuit protection. Short circuit protection is something that most electronic devices should have. If it has a lithium battery it SHOULD have short circuit protection because they can put out sufficient current to cause fires. The battery will be shut of if there is either high current or the battery has dropped down to the cutoff voltage. Lithium batteries are damaged if the votalge drops below a certain level. If you pour water into the device is won't necessarily shut off the battery because it won't detect an abnormal level of current consumption.
It is likely to be the battery. There may be mobile phone repairer in your area that can replace it. You can do it yourself if you have the skills. Here is a youtube video on how to do it: https://www.youtube.com/watch?v=_I2uLqRg...
It looks like the light is powered at the same time as the motor. therefore the fault is the motor itself. It is possibly the brushes. There is a slim chance that you could repair the actual motor (it is not a serviceable part) depending on the fault otherwise you will have to replace it.
Hey Dan. Are you the Dan Rae in NZ? I don't know that particular model but the fault may be the paper separation pad. It sits below the paper feed roller and may have become glazed. Either replace it or buff it up somehow.
It is difficult to give an exact answer from your question since more information is needed. To narrow the fault down a technician will make a number of observations and tests. You have made a start but here are a few more: (1) Is the display indicating anything? Since you outlet is working it is therefore a fault in the microwave. (2) Unplug the microwave and remove the covers. There is usually no safely issues in working on an unplugged microwave except that on very rare occasions the high voltage capacitor may remain charged. Shorting it is a quick indication whether is charged and will also make it safe. (3) Check the main fuse (usually located on a circuit board where the power cable terminates. (4) If it is blown there would be any number of causes including a power surge, faulty door switches, etc. A technician will be able to determine the cause.