Phone won't turn on
The phone won't respond to any button presses and does not turn on.
The most common cause of this problem is that the battery is either faulty or incorrectly placed. Simply remove the battery and replace it to see if this is the cause.
Another part that could complicate startup on the phone is the motherboard. If the motherboard is faulty then the phone will be unable to run its processes, such as the ones responsible for starting up. Replacement of this part is advised if this is the case.
Phone won't charge
When plugged in the phone fails to charge.
Broken charging port
If the charging port is broken the phone will be unable to register the charge. If this is case make sure to replace the port as soon as possible using this guide Samsung Galaxy S4 Mini Charging Assembly.
Faulty Charging Cable
Another possibility is that the charging cables could be faulty. It may be wise to try switching out the cables before opening the phone to check the charging port.
Lack of Storage
If you try to install any new apps or take any new media you are unable to save it.
Memory card is full
If you're finding that you cannot install anything new or save any pictures it is most likely due to the fact that the memory card on the phone is full. If this is the case your options are to delete things off of the card to make room, or try to upgrade your card to have more space.
The phone is hot to the touch or warmer than you would want consistently.
For most electronic devices, ventilation is key. If your phone is consistently in a position that air cannot circulate around it, make sure to remove it from said location and allow it time to cool off.
Using old SIM cards
Interestingly enough, using old SD cards can cause your phone to have to work extra hard to decrypt old corrupted data. Switching to a new card can help alleviate these issues.
Phone doesn't play any sound
When trying to watch videos or use applications that have sound, nothing comes out.
Make sure the volume is not turned off
The most common source of this problem would be forgetting to unmute the phone. Some phones will automatically unmute themselves when playing media but if you're not sure, check your phone while playing something
If no sound is coming out of the phone its probably best to check the part of the phone that is responsible for this, the speaker. Replacing of the speaker will allow the phone to play sound again.