iMac G3 Flower Power display is all lines

Try resetting the PRAM:
http://support.apple.com/kb/HT1379?viewlocale=en_US

If that does the trick you have a weak / dead battery, and it should be replaced. If it does not help, your guess "Is the display shot?" is probably the right answer.

Sounds to me like the video is shot. And no, there is such thing as a cheap repair. But you might find a used iMac for a very reasonable price, say $50. There are many such being sold on eBay, but the cost of shipping negates the low cost of the computer. Perhaps you will be lucky, and find one on eBay that is close enough for you to pick up.

Here's one, just as an example: http://cgi.ebay.com/Apple-iMac-G3-400-mhz-256-mb-20GB-Tiger-10-4-11_W0QQitemZ330 238412305QQihZ014QQcategoryZ111418QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Hello There,
Don't throw it in the bin, you can take the case off and put it on another iMac G3 and then you'll still have a groovy flower power (like me!!)