Lock after restart

[mtmtppp]

When I restarted my device XZ3, I failed entering passcode. And then, inputting the word "SONY" was required to unlock the device, however, I was unable to enter the word because only numeric keyborad was available. Therefore, I repaired my device with Xperia companion.
For the next time when I failed entering passcode after restarting device, I would like to know how to use word keyboard.

[Lord_viridis]

What happens if you hold the keys down?

[mtmtppp]

Thanks for your reply.

Nothing happened on holding the key down.

[Lord_viridis]

Are you tapping on the line below the word Sony?

Can you screenshot the text entry you get come up.

[mtmtppp]

Yes, I tapped.

When I try to take the screenshot, the keyboard is hidden so I can not take it.