Situation

# 7.2.4版之後，密碼重製無法使用maintainer帳號
Starting from version 7.2.4, password reset can no longer be performed using the maintainer account.

Solution

1. 
FortiGate reload > Enter

2.
[C]: Configure TFTP parameters.

3.
# 設定 fortigate local ip address
[I]: Set local IP address. 

4.
[T]: Set remote TFTP server IP address.

5.
[F]: Set firmware file name.

6.
[Q]: Quit this menu.

7.
[T]: Initiate TFTP firmware transfer.

8.
Please connect TFTP server to Ethernet port ‘WAN2’. #接到FortiGate的WAN2

9.
Image Received.
Checking image… OK
This firmware image is certified!

# 設定開機的時候預設使用
Save as Default firmware/Backup firmware/Run image without saving:[D/B/R]? 
D 

10.
Programming the boot device now.The system must re-layout the boot device to install this firmware.
The default and backup firmware will be lost.

# 重開機
Continue:[Y/N]? 
Y 

11.
config system admin > edit admin > set password "myPlainPassword"