To fix the "middle 2 LEDs staying on problem" with Mavic Air batteries:
1) If you have a fully charged FUNCTIONING Mavic Air battery, skip this step. If not, fully charge a functional Mavic Air battery (borrow a functioning battery if you only have 1 battery and it's malfunctioning).
2) Download DJI Assistant 2 V1.2.2.845, and install on your computer.
3) Charge your malfunctioning battery(ies) for at least an hour. Ignore what the LEDs do during this hour.
4) While your malfunctioning battery(ies) is charging (or if it has just charged for at least 1 hour), install a fully-charged FUNCTIONAL battery into your Mavic Air.
5) Start DJI Assistant 2.
6) Connect your Mavic Air to your computer.
7) Turn on your Mavic Air.
8) Select your Mavic Air in DJI Assistant 2
9) Update your firmware to V01.00.0300.
10) Update the rest of your fully-charged functioning Mavic Air batteries.
11) After your malfunctioning battery has charged for at least 1 hour AND after you've updated your Mavic Air aircraft to firmware V.01.00.0300, install your MALFUNCTIONING battery into your Mavic Air.
12) Turn on your Mavic Air.
13) Update to V.01.00.0300. Your first attempt will likely result in a failure notice citing the reason as your battery not being fully charged. Leave that screen up for at least 1 minute. If the update doesn't resume installing on its own, click Retry. Then your malfunctioning battery will resume and complete the firmware update.
13) Your malfunctioning battery should now be fixed!
Hope this helps!