Flip out the batteries for one minute, then put them back in place.
Try replacing the batteries. If you use rechargeable batteries, this may be defective.
Try connecting the Archos to a computer, and see if it start connected to a computer. If it starts go to the screen Settings > System and press and hold the DOWN action button for three seconds. A button "Format HD" will appear. Use this button to format the AV 700's hard drive. Doing this will erase all the data on the AV 700's hard drive.
If the unit starts up, try also updating the firmware. Here the page.Here how to install.
Try entering in recovery mode.:
To enter into the Recovery screen
Turn off the device and wait 10 seconds.
Press and hold the volume +
button while powering on the device.
Keep the volume +
pressed until the Recovery mode starts (white screen).
To move from one option to another, use the volume buttons. To select an option, press the ON/OFF button.
Recovery mode options
: Cancels the system recovery.
Allows you to connect your device to a
computer in order to copy the latest .AOS file (operating system) to
your device and then install it.
: Attempts to repair the file structure on the internal memory. This does not erase any data.
: Return to main recovery screen.
Force Touchscreen Calibration:
Select this and then select
no to leave the recovery screen. Upon restarting, the ARCHOS will
immediately start the touch-screen calibration utility.
Check and repair the system partition if damaged.
Start USB MSC
: Allows you to connect your device to a PC to access the internal memory.
: Formats the internal memory. All data (music, photos, videos, etc.), applications and settings are erased. "
If all that does not work, contact Archos and book a repair.
Here a manual.