Samsung Galaxy S21 Ultra: Full Teardown & Reassembly Guide

Samsung Galaxy S21 Ultra: Full Teardown & Reassembly Guide 🛠️

If you’re curious about what’s inside the Samsung Galaxy S21 Ultra or planning a repair, this guide has you covered. We’ll walk you through the teardown and reassembly process in simple steps, highlighting all the key points to keep your phone safe and functional.

🛠 Tools You’ll Need

Polar Tech Magic Self-Heating Pad
Polar Tech Phone Repair Toolkit (Isopropyl alcohol ,Metal shim, Plastic pry card, Tweezers, Spudger, Precision screwdriver set)

Step 1: Heating & Removing the Back Cover

Before touching anything, power off the phone. Safety first!

Grab your toolkit and two PolarTech Magic Self-Heating Pads. Place them on the back and heat for 10 minutes—this softens the adhesive holding the back glass.

Once heated:

Use a suction cup to lift the back slightly.
Insert a metal blade into the gap and drip some alcohol to weaken the glue.
Slide a plastic card around the edges to carefully release the adhesive.

Tip: If the back feels stuck, add a little more alcohol. Patience here prevents cracks!

Step 2: Removing Components & Screws

With the back off, it’s time to tackle screws and connectors:

Remove the screws from the top frame using a magnetic mat to keep them organized.
Disconnect the battery connector first, then all other flex cables.
To remove the battery, drop alcohol around the edges, then gently pry from the side with a metal tool.

Next, remove other internal components:

Earpiece and motherboard screws (5 screws)
Sub-board screws (4 screws)
SIM tray and sub-board flex cable
Short screws (3 pieces) holding the sub-board

Carefully lift components with tweezers. Be especially cautious with the front camera, which has waterproof adhesive. Use a thin blade to loosen it, don’t pull hard.

Finally, remove the vibration motor and the antenna module using a Y-type screwdriver (7 screws total).

Step 3: Installing New Parts

Reassembly is basically the teardown steps in reverse:

Antenna module first, making sure all 7 screws are secure.
Vibration motor and motherboard, reconnecting the front camera flex cables carefully.
Install the battery and sub-board but don’t reconnect the battery connector yet.
Double-check every FPC and tighten all screws, including the three short sub-board screws.

Tip: Don’t rush. Missing a cable or screw can cause bigger problems later.

Step 4: Sealing & Testing

Install the sub-board shield and reconnect the battery.
Reinstall the mainboard shield and all remaining screws.
Finally, place the back cover. If the adhesive isn’t strong enough, add a bit of fresh glue.

Your Samsung Galaxy S21 Ultra is now fully reassembled and ready to power on!

Final Thoughts

This teardown and reassembly process can look intimidating, but with the right tools, patience, and attention to detail, it’s very doable. Whether you’re repairing a broken back glass or replacing the battery, following these steps keeps your phone safe and functional.

Don’t forget: organize screws, handle flex cables gently, and take your time!

📩 Need help with your device?

If you have any questions or need further details,contact us or leave a comment below. We’re always happy to help.

👋 See you in the next one!