G Pro X Superlight Red LED

In the last 2 days, the LED seems to be stuck in red. This appears to be a hardware issue, and persists across different PCs.

Steps to reproduce:

• Use receiver, not cable
• Turn mouse off
• Turn mouse on
• The LED goes orange
• After a few seconds, the LED changes to red.

Despite being fully charged, the mouse never goes to 'green' and the LED never turns off.

The battery is draining much faster than it used to.

What is wrong with the mouse? What can I do to fix it?