It sounds like your Archos may have been doing a system update and was warning you not to turn the unit off during that update. Normally you could try and reset the unit to make it functional, but since you have already tried that process we will have to try a System Recovery. Fortunately the Archos does have a recovery process built into it, and you will have to take the following steps to run that process.
The first thing you will have to do is get the unit to start the recovery process. You should do the following:
1) Press the power button to turn on the unit.
2) Once the LCD screen turns on immediately press and hold the TV/LCD button until you see that the recovery mode has started. You should see a white screen on the LCD.
3) On your 605 you will need to navigate using your up/down buttons. Once the correct item is highlighted you will press OK.
4) You should see several choices on the recovery screen. The one you will be choosing is the
Repair Disk option. The system will attempt to repair your files without actually erasing any of your data that you have saved to it. If this option fails you will the have to try the
Format Disk option. This will reformat your disk, but in the process it will wipe out any and all data that you have saved to it. You will then have to reinstall any information that you had saved to the disk.
Once you have reformatted the disk you can then go ahead and reinstall the firmware for your unit. You can do this by using a computer to go to the following website:
http://www.archos.com/support/support_tech/updates.html?country=ca&lang=enThe first box on the page is titled
Firmware. You will use the drop down menu in the box to choose your model number and then download the latest firmware for your unit. Once you have chosen your model number the screen changes to a download screen that you will download the software from. Directly underneath the link for the download is a link that explains how to install the firmware This is the link:
How to install a firmware.Following those instructions should get your firmware installed and then allow you to once again use your unit.
If you are unable to get to the system recovery menu, or the unit will not allow you to either repair or format your disk then there is a defect inside your unit. If you have any warranty left on your unit you can take it to your local Archos repair center and have them fix it for free under the warranty. If the warranty has expired then you will have to pay for any repair out of your pocket. Due to the high cost of the labor for repairing electronics (some shops will charge up to $150.00 an hour for labor) you should get an estimate for the repair. You can then decide if the repair is worth doing.
These steps should allow you to resolve your issue. If you do have further problems please don't hesitate to let us know. Thank you for the opportunity to assist you in resolving your issue.