Sentinel Extraction Terminal

As clued by Sentinel Extraction Terminal first letters, these puzzles are a game of SET. Each group of 12 sentinels is 3 valid sets with 3 extras. The rules of SET in this instance would dictate that all the items of a trait must match, or must be different. The highlighted groupings for Group 1 are below.

The three unused sentinel images have two sentinels with a matching trait for each trait type and one different. The different traits are collected below.

Base Armor: Ice Head: Laurel Face: Crystallized Body: Lab Coat

The sentinel with these traits is 2116

The highlighted groupings for Group 2 are below.

The three unused sentinel images have two sentinels with a matching trait for each trait type and one different. The different traits are collected below.

Base Armor: Ice Head: Spikes Face: VR Headset Body: none

The sentinel with these traits is 718

The highlighted groupings for Group 3 are below.

The three unused sentinel images have two sentinels with a matching trait for each trait type and one different. The different traits are collected below.

Base Armor: Runes Head: Black Headphones Face: Crystalized Body: Black Hoodie

The sentinel with these traits is 104

The highlighted groupings for Group 4 are below.

The three unused sentinel images have two sentinels with a matching trait for each trait type and one different. The different traits are collected below.

Base Armor: Runes Head: Undead Spikes Face: Fire Eyes Body: Trippy T-Shirt

The sentinel with these traits is 500

The 4 found sentinel numbers 2116, 718, 104, 500 can be broken up as indicated by the number symbols below each grid to read 21 16 7 18 1 4 5 which can be converted to read UPGRADE