Broken galaxy s2 g9100 with odin - how to fix?

ive broken galaxy s2 g9100 with odin - how to fix ?
its now only turning on shows a screen for split second when i press a long continus press but after that its dark again

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

Try to boot into recovery mode …(volume up + home + power)
If you can, there are solutions,
if not, embedded memory could be definitively broken.

im able to boot to download mode. but it appears only for a second …

That’s sounds strange, have you read Know your hardware - Samsung ?
Are you sure about your battery ?

Can you tell us, what is the reaction when you try to boot to Recovery mode?