Samsung Galaxy S3 — Factory Reset STUCK! Help!

Hello, I am really worried about my phone because I have had it for around 2 years and I considered factory resetting it today morning and I did and it has been showing me "Downloading..." screen for 7 HOURS! I know it says don't turn off device, but I have taken out the battery several times and it still shows up the same screen. Please help I can't afford even a nokia and I don't know what to do!
It shows a black screen with android icon and big text - Downloading... and below that Do not turn off target!! And then in the top left corner it shows Could not do normal boot. DOIN MODE. Product name: GT-I9300I. Current Binary: custom. System status: custom. QUALCOMM SECUREBOOT: ENABLE (CSB)
RP SWREV: S1, T1, R1, A1, P1.
UDC START

ITS DOING THIS FOR 7 HOURS! HELP!
PLEASE! ASAP! :C

Okay basically what I did was I removed the battery so the phone shuts down and then I pressed ONLY the power on button not any volume buttons.

And then the downloading screen showed up.
I would really appreciate it if you would know how to fix this.
I'm sorry if I talk bad english I am very stressed!

This is too hard, I can't do it, is there a possible way that you or someone can set this all up for me in teamviewer or somehow? And I don't see Latvia as a country in "correct firmware".

I am going to be dead if my parents will know this please help can you set it up for me I am not good with phones I don't understand anything.

Okay, yeah its really hard and I'll just pay the 20$ to fix my phone. I hope they will really install the right version though.
Thanks so much for the help, this was the most useful site I found for this situation, I hope you're getting paid enough for this job because you sure are a great staff and admin!
10/10 on the service!

Thanks so much again!
I'm going to tell my friends about this website.

Okay, so I went to the technician or whatever you call the guy who fixes phones and he said my phone has a damaged part somewhere that makes it not working sometimes propertly. The phone technically still works, I tried even internet and instagram works, so I gave it to my grandma for internet. And I got a new phone - Samsung Galaxy A5 and my mom wasn't even so mad.

Yet again, without this website I wouldn't have survived.
10/10 service, love it and you're awesome!
I wish you a great week! I'm very happy with my new phone!