WITH i-ELOOP

Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .)
While pressing the main fuse cover hook in the direction of the arrow (1) shown in the figure using a tape-wrapped flathead screwdriver, lift up the main fuse cover in the direction of the arrow (2) to detach the main fuse cover hook from the main fuse tab.

Fig 1: Pressing Main Fuse Cover Hook Using Flathead Screwdriver
Courtesy of MAZDA MOTORS CORP.
Remove the main fuse cover.
Remove the nuts.

Fig 2: Identifying Front Wiring Harness, Short Cord And Main Fuse Nuts With Torque Specifications
Courtesy of MAZDA MOTORS CORP.
Remove the main fuse.
Install in the reverse order of removal.