2450 Battery you need - https://amzn.to/3OLOV4Y

Here is a quick and simple video on how to change the weak or dead battery in your Grand Highlander key fob. This does not require and tools. You will just need 1 replacement 2450 battery. First, use the mechanical key to pry the two halves apart. Then use the same key to remove the dead 2450 battery. Place your new battery in + side facing up and clamp them back together. You're all set! No need to reprogram. Hope you found this helpful! Take care.

OEM 2024 TOYOTA GRAND HIGHLANDER SMART KEY LESS ENTRY REMOTE FOB HYQ14FBX
2024 Toyota Grand Highlander / 4-Button Smart Key / PN: 8990H-0E330 / HYQ14FBX (OEM)
FCC ID: HYQ14FBX
Frequency: 315MHz
Battery: CR2450
Buttons: Lock, Unlock, Hatch , Panic
Aftermarket Emergency Key: EKB-TOY-M20
Test Key: LXP90
PN: 8990H-0E330
2024 Toyota Grand Highlander