K350i Only turns on sometimes and freezes a lot.

Hi,

I'm new to the forum, but I've been checking it out and you guys are great with phones! My hat is off to you!

The thing is I have a SE K350i which only turns on sometimes (sometimes I have to tap it a few times and it will boot...sometimes it gets hit and crashes). But I generally dies quite quickly without me doing anything. It started freezing once in a while and the only way to get it back was to remove the battery. Then it started happening more often until there were times where it wouldn't turn on for a while.

Also, when I try to connect to XS++, it only is detected when I am able to turn on the phone. If it doesn't turn on, then the computer won't recognize it. (I don't mean that I connect it to XS++ with it turned on)

The battery is ok, I used it in another SE and it worked.

I tried updating the firmware and the only thing it did was lock the phone. (A friend told me to do this, but he didn't warn me it would lock my phone).

What I want to know is: Is this a software or hardware problem?

Is my phone dead?

Thanks in advance!