Here's the method I was sent from Kobo support when you cannot access menus. It works for me.
Please complete a factory reset on the device. To do this please follow the steps below :
i. With the device powered off, press and hold down the Home button.
ii. Move the power slide to the right, then let go. The power light should blink red twice.
iii. When the light turns green, let go of the Home button.
iv. The light should start to flicker white, and will continue to flicker while it resets itself.
Once this is complete the device should power up. Connect the charger and the screen should say connect and charging.