Sunking2498,     You can find the update here, and steps to update from page 4 here.    Let me know how it goes.    
Hi, I am planning on upgrading my Dell S4148-F switches with the latest OS10 update and was looking to also update the switch firmware using the ONIE.bin file however I can't find this in Dell Digital Locker.  I have access to a large number of OS10 versions including the latest but nothing for ONIE.  Has the firmware upgrade process changed at all?   Thanks in advance!
Firmware Updates for S Series Switches