Many users fail because they install the update before the base game. Here is the correct sequence using a tool like DBI, Awoo Installer, or Tinfoil:

In the world of Nintendo Switch homebrew and custom firmware (CFW), an NSP file is the standard format for installing digital games. Just like official games receive patches from Nintendo's servers to fix bugs and improve performance, these updates are also extracted and distributed as NSP files—often labeled as "NSPupd" or Update NSPs.

Installing an update NSP essentially patches the base game, applying developer fixes without requiring a full re-download of the main title. For a game like Need for Speed Hot Pursuit Remastered, which relies heavily on fast rendering and online connectivity, staying on the latest version is crucial.

This is the number one reason why an NSP doesn't "work." Nintendo Switch games require cryptographic signatures. Since you are not buying the game from the eShop, CFW needs to bypass this.

Fix: Download the latest sigpatches (from TotalJustice or ITotalJustice) matching your Atmosphere version. For example, Atmosphere 1.5.4 requires sigpatches v16. Merge the atmosphere folder to your SD card and reboot.

After installing v1.0.3, the game may still prompt you to connect to the internet to "verify" the software. Because this is an NSP, Nintendo’s servers will reject it.