Frozen 'off screen' with white horizontal lines

My Kindle Voyage worked perfectly and then suddenly all I got was the 'off' screen with 3 horizontal white lines. I've tried holding the on/off button for different lengths of time but it has no effect. Help please.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0

crwdns2947414:01crwdne2947414:0:

I know you've said that you've held down the power for various amounts of time, but have you held it down for 40 seconds as recommended here:

https://www.amazon.co.uk/gp/help/custome...

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

crwdns2934285:0crwdne2934285:0