Can't boot Ubuntu partition after replacing the motherboard

Computer specs:
Model: Dell XPS15 9550
Processor: Intel i7-6700HQ
GPU: NVIDIA GeForce GTX 960M
RAM: 16GB
Storage: 1TB SSD
Dual boot Ubuntu 18.04/Windows 10

After replacing the motherboard of the computer, the BIOS configuration was set to default and the Ubuntu partition was undetected. Windows partition remained intact and healthy. Following I made these changes to the BIOS in order to reestablish the partition:
-Disabled Secure Boot.
-In Boot List Option (set to UEFI), added a Boot Option Ubuntu with Filename: /EFI/ubunt/shimx64.efi

With those configurations I got the following error during boot:

ACPI Error: Method parse/execution failed \_T2.FN04._ON, AE_NOT_F  
acpi PHPOCOB:04: Failed to set initial power state  
ACPI Error: [\_SB_.PCIO.LPCB.H_EC.EC.ECAV] Namespace lookup failure,  
ACPI Error: Method parse/execution failed \_T2.FN04._ON, AE_NOT_  
ACPI Error: [\_SB_.PCIO.LPCB.H_EC.EC.ECAV] Namespace lookup failure,  
ACPI Error: Method parse/execution failed \_T2.FN04._ON, AE_NOT_  
ACPI Error: [\_SB_.PCIO.LPCB.H_EC.EC.ECAV] Namespace lookup failure,  
ACPI Error: Method parse/execution failed \_T2.FN04._ON, AE_NOT_  
ACPI Error: [\_SB_.PCIO.LPCB.H_EC.EC.ECAV] Namespace lookup failure,  
ACPI Error: Method parse/execution failed \_T2.FN04._ON, AE_NOT_  
Couldn't get size: 0x800000000000000e  







PKCS#7 signature not signed with a trusted key  
PKCS#7 signature not signed with a trusted key  
PKCS#7 signature not signed with a trusted key  

After that I am prompted to a Busy Box v1.27.2 (ubuntu) built-in shell (ash)
(initramfs)

Please advise on how to get my partition back up. From the Windows partition I can see that the partition is "healthy" I also tried by configuring the BIOS SATA Operation" from "RAID On" to "AHCI", but I get a blue error screen instead.