Edit the following sentence to correct any grammar mistakes and make it more concise: 

"The phone has a not charging issue because it ran out of battery."
"The phone isn't charging because its battery is drained."
Complete the following task based on the instruction and optional input provided.### Instruction:
Edit the following sentence to correct any grammar mistakes and make it more concise: 

"The phone has a not charging issue because it ran out of battery."

### Output:
"The phone isn't charging because its battery is drained."