Sometimes laptop keyboards are held in by retracting clips, as well as screws on the bottom.
Firstly: look for any remaining screws that may have a keyboard symbol next to it. Remove them.
Next: You see on your new keyboard where the "clips" are? Look on your current keyboard, and see if you can use a small screwdriver to push any retractible clips back (they should slide back easily - don't force anything or you may break the plastic clips or something like that.
Laptop: MSI GT70 2OC-059us | i7-4700MQ | 16GB | GTX 770m | 500GB SSD / 750GB HDD | 17.3" | Win10 Pro
Desktop: 4690k | 12GB g.Skill RipJaws | GTX 970 | 520hx | Z87X-UD4H | Corsair Vengeance C70 | Corsair H110 | Acer 25" | Acer 22" | Win10
Mobile: Samsung Galaxy Note 5
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