C:\Users\user\AppData\Roaming\Suuntolink
open suuntoapp.log
 
search for this url:
[2018-May-17 10:47:49 +0300] [DEBUG] WebService::create. appKey=xxxyyyzzz, serviceUrl=https://uiservices.movescount.com, thruJuche=0
[2018-May-17 10:47:49 +0300] [DEBUG] Arrest: GET using URL https://uiservices.movescount.com/devices/Amsterdam/A?appkey=xxxyyyzzz&maxfirmwareversion=9.9.9
 
Go to url above ^ which gives you the download link to firmware
 
{"DeviceName":"amsterdam","FirmwareUploadDate":"2018-05-17T07:24:13ZZZ","LatestFirmwareURI":"http:\/\/firmware.geo.movescount.com\/production\/Amsterdam-fw_2.0.34.5939-A.zip","LatestFirmwareVersion":"2.0.34.5939","Version":"A"}
 
Seems to work for other devices the same way, just replace Amsterdam with Cairo or your device name in the url...

Remember to select right firmware for your watch, see corresponding version names below.
 
'Amsterdam': 'Suunto Spartan Ultra',
'Brighton': 'Suunto Spartan Sport',
'Cairo': 'Suunto Spartan WHR',
'Forssa': 'Suunto Spartan Trainer',
'Gdansk': 'Suunto Spartan WHR Baro', 'Suunto Spartan Sport Wrist HR Baro', 'Suunto Spartan WHR Baro',
'Helsinki': 'Suunto 3 Fitness',