EC2 root file system is read only after reboot

We created a new EC2 instance (t2.medium). After a reboot, the root filesystem became read only, so cannot do anything on the system /dev/xvda1 on / type xfs (ro,relatime,attr2,inode64,logbufs=8,logbsize=32k,noquota) [/]

Any idea how to fix this? I tried xfs_repair -d and then rebooted, but the filesystem is still read only