Amiga 500 problems

[snowwalker]

Hi guys

I've just put my old amiga 500 out of storage after 2-3 years and unfortunately the system dont work anymore , the screen goes yellow and the power ''red light'' flash 11 times then nothing happen

any answers would be appreciate

Thanks

Martin

[snowwalker]

I removed the memory expansion and it's now working fine , if the problem is the battery can I change it?

Thanks guys for the help