Amiga A2000 powers up but does not start

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Hi I have a Amiga 2000 which has been stored for a while. I powered it up today and everything runs but it does not boot up and put anything on the screen. If this was a PC then i would think the internal battery was at fault. As i know nothing about Amigas and it was purchased in Germany all books are in German. Can anybody help me?
Rgds Chris

[storm]

HI
  It is the original Highscreen one that was purchased with it and has the number KP748/30E on the back. I have noticed that the battery has some white corrosion on it but has not yet affected the cicuit board.

[storm]

Hi
there is not drive activity or clicking when switched on.
The Monitor only has Highscreen printed on it and was supplied new with the A2000 when i purchased it in 1990. The screen comes on white and then changes to grey when the Amiga is switched on.If i Remove the battery will it run without it or do i need to replace it.I have only ever used the Amiga as a games machine so am a novice when it comes to the parts within. I am used to fixing PC's so my knowledge of the Amiga is limited.
Rgds Chris

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Hi
  I have just turned it back on again and am now getting a red screen. I read on another site that this is a ROM failure.Can anyone explain please.

[storm]

Hi
  I have checked it an it looks fine. The battery corrosion is only on the battery and there is none on the mother board. I have pushed the board to make sure it is fitted OK. There are no cards in it as it is as it was when brought brand new and has had no additions put on it. The Mother board is a amiga B2000-cr Haynie/fisher A/w 912723 Rev 4 and it looks brand new.