husqvarna · Automower Technical Manual
The blade disc is blocked by an object, or the blade motor itself is defective. This could also be a control box or main cable issue.
Click steps to track your progress.
Check the blade disc for grass or other objects and remove them.
Test the blade motor speed via 'Tools - Test - Power & Motors – Blade motor' (shortcut 5-2-1-2); the speed should be about 2,500 rpm (or 1750 rpm for 260 ACX).
Inspect the cable harness and connector for damage and repair or replace if necessary.
If problems persist after checking for obstructions and cable damage, the control box may be defective and needs replacement.