Phone wont turn on except when connected to charger

Ok so first time i had problems like this was when my battery was like <30% and i take a photo with flash it turns off with no warning instant shutdown , then i had battery fluctuation if battery was like 8% when i offline charge like for 5minutes when i turned it on was 34 - 50 % . Now my phone wont go pass lg boot logo or it passes and get to homescreen it will insta shutdown , this happens even with 100% battery .Im on stock 4.4.2 v20a eu . Can someone help please ? i suspect the battery but i wan to know if someone else had problems like this before

Flashed Rom, everything works, except can't get Data (3G)

Hi All,

This is really weird, i never had this issue before of all these years of flashing.

Just flashed it to ArchiDroid (amazing btw):

Build Number: ArchiDroid-3.1.3-STABLE-LMY48G-CyanogenMode-i9300

BaseBand: i9300NEUGOA1

IMEI: fixed after using EFS v2 baseband.

APN: Its all there. I'm using Fido (Rogers) in Canada, North America

I can make calls, but i have the "!" sign beside the signal bar, and i can't seem to get data/internet.

Open to any suggestions or opinion, i have no idea what's going on.

Thanks and Regards,
Kev84