Samsung Galaxy S2 turns on but freezes after 5 seconds

[jusennos]

Hello, I have problem that my galaxy s2 turns on, but when i have entered my pin code it works like 5-15 seconds, downloading frontscreen and i can go to menu if i'm quick enough, but then it freezes. Is there any solution to fix this problem? Why it freezes?

I kept my phone turned off whole night and when i started it, it worked like 5 minutes and i was able to download from play store whatsapp and instagram but then it freezed again.

I dont have SD-card in my phone!

What I have tried to do
-Pull out battery and put back in -> still freezes
-Pull out battery and sim card and but back in -> still freezes
-I have done hard reset on my phone -> still freezes
Any ideas?

 

[jusennos]

Now it's been working good like 10 minutes, just re-booting it. But battery has gone from 70% to 40%. So is this a battery problem?