do i have to open the lower portion and thighten the inner screws or just the the bottom screws?

This post helped fix my issue with the sudden shut downs. I did three things.
1. Updated my BIOS
2. Removed the memory compartment and reattached the cover, tightening all the screws.
3. Did the battery reset as instructed on the Acer support page.

Since I followed those three steps, there has been no problems. Six full cycles on battery power with unexpected shut downs.

AN515-51
BIOS ver 1.15

It happened again today   This laptop sucks. I am in netherlands and who should I call regarding problems with the laptop?

I have the same problem. The service center guy just reinstalled OS and said it will suffice. But the problem still exists in my nitro 5. Does above mentioned solutions working fine in long run or are temporary solution? 
Waiting for the reply. Thanks.

We just bought the Acer Nitro a couple of weeks back and have had the same problem. After a little research we noticed it could be the magnetic switch at the left front. Every time my wife would set her wrist down to start typing the screen would shut down. The issue for us is she wears a Fitbit on her left wrist and the neodymium magnet on the band would rest real close to where that magnetic switch is and kill the screen. I had her remove the Fitbit and since then she has had no issues. I also confirmed that it’s the switch by running a magnet over the area where the switch is and every time I did the screen would shut down. Also, if you run a magnet over the top left of the screen the magnet will stick to the magnet that is imbedded at the top left of the screen frame. We tightened the screws, reset the battery and the Bios is up to date but it still gave us issues till we figured out the cut-off switch issue...now...problem solved.

Tighten the screws on the laptop's backside. Worked for me.

Tombakek said:

Hello,
My Acer Nitro 5 shuts off whenever it wants when it's not charging. I don't play games, watch high quality videos or anything. Please help me.

When I first bought the Acer Nitro 5, I had the same problem so they exchanged it. Now 2 years later (warranty expired) this laptop started doing the same thing. Sometimes it cut out randomly when not charging and sometimes instantly when disconnecting from the charger (but always happened when NOT charging). So it seemed like a problem with the battery. I tried tightening all the screws underneath the laptop but to no avail. What DID work however was doing as suggested at the end of this thread: Placing electrical tape on the protrusion on the RAM cover that presses the battery kill switch. This is to ensure that it presses the switch properly when closed. So in short IT WAS THE BATTERY SWITCH IN THE RAM SECTION.