Review of failed replacement of a battery

Hi guys,

I tried battery replacement for my Google Pixel 2 and failed it.

I accept my failure this time and will get a new phone, but wanna win next time.

I would appreciate it if you could help review the failure.

Replacement process:

I got a battery replacement kit for Pixel 2 from iFixit and followed the instructions (Google Pixel 2 Akku austauschen).

After placing everything back, the phone did not turn on.

Symptoms:

The display does not show anything.

The new battery is supplying power to the device because it vibrates momentarily when I touch the fingerprint sensor.

When I connect the device to the charging cable, it makes a long vibration (an indication of battery charging starting).

A long push of the power button does not make a long vibration (an indication of the device turning on).

Mistakes:

When the display panel is opened, the opening pick got into between the cover glass and the thin display film, causing a part of the display to detach from the glass.

When the midframe was removed, I did not notice the metallic tape attached to the top left of the frame (picture attached) must have been peeled. I found it after I tore the tape off.

Questions:

Is it possible to identify what the fatal mistake was causing the issue?

What is the function of the metallic tape I tore?

Any chance to revive the device?

Thanks,