One of the pre-tournament fancies behind hot favourites India, England stumbled through their group matches.
The 2022 champions lost comfortably to the only Test-playing side they faced, the West Indies, and were unconvincing in wins against associate nations Nepal, Scotland and Italy.
"I think there's definitely a little fire in all of us to kind of really go out there and push the players to the top of their performances," Bethell told reporters.
Brook's side have returned to their happy hunting ground in Kandy after playing all their group matches in India, at Mumbai and Kolkata.
On Sunday, England will kick off their Super 8s campaign against co-hosts Sri Lanka at the venue where they swept a T20 series 3-0 this month.
"We're coming back to conditions that were foreign a few weeks ago, we then got to know him over three games here," said the left-handed Bethell, who bats a number three.
"We beat them 3-0, so I think we're definitely coming back to this part of the world with a lot of confidence."
Bethell said he had watched a lot of matches on TV during the tournament and had been impressed by Sri Lanka's Pathum Nissanka.
The opening batsman scored the first century of this T20 World Cup as Sri Lanka beat Australia.
Bethell admitted Nissanka would be dangerous on Sunday.
"I thought Nissanka played unbelievably," said Bethell.
"You know, he actually got off to a few flyers against us. But that really showed what he could do."
The 22-year-old said it was important not to dwell on England's stuttering group stage campaign and move on.
"I think everyone had the same mindset of, all right, the main thing is just to get through to Super Eights," said Bethell.
Effectively, a new mini-tournament now begins, with Sri Lanka, Pakistan and New Zealand to face. Only two will progress to the semi-finals.
"So now we're here, then this is where the proper competition starts," said Bethell.
Bethell is England's top run scorer with 143 at an average of 35.75 with one fifty in their four matches to date.
Explosive openers Phil Salt and Jos Buttler have failed to fire so far, as has captain Brook.
Bethell is confident that will change and England's much-vaunted batting line-up will soon be back to their destructive best.
"I think everyone just has that underlying feeling that we're going to turn that corner," he said.
"We're winning games of cricket, and we're not firing.
"So imagine when we do."