Let's be realistic. Some issues are physical. If you have tried every listed above and the device still refuses to hold a charge for more than 10 minutes, the lithium battery has reached its end of life. These batteries are generally soldered to the board. Unless you are proficient with a soldering iron (seeking a 3.7V 402030 Li-Po cell replacement), it is time to purchase a new unit.
: If the problem persists, consider uninstalling and then reinstalling the application. This can sometimes resolve issues related to corrupted files. candid+hd+castle+3+fix
Does your Castle 3 turn on, show the logo, and then shut off repeatedly? This is known as a boot loop. Let's be realistic