One of the 21 July bomb plot suspects has shown a court how he claims he dismantled a booby-trapped sideboard.
Mr Asiedu told the court he thought chemicals were for cosmetics
Manfo Asiedu, 34, wearing purple gloves, demonstrated to Woolwich Crown Court how he says he opened the door and pulled out the battery.
Mr Asiedu's legal team earlier claimed his actions could have saved the lives of everyone in a London tower block.
Six men deny conspiracy to murder and to cause explosions across London's transport network on 21 July 2005.
Mr Asiedu, of no fixed address, told the court: "I opened it slowly. When I saw the battery what I did was I put my hand (in) and I pulled the battery."
After demonstrating his actions to the jury, he told how he went on to pour a tub full of hydrogen peroxide and flour mixture down the toilet.
His defence barrister, Stephen Kamlish QC, had earlier told the court that in doing so Mr Asiedu was possibly responsible for "saving the block and all the people in it".
Two months into the trial, Mr Asiedu had turned on co-defendant Muktar Said Ibrahim and accused him of planning an attack "bigger and better" than 7 July's attack on the London Underground.
He also claims Mr Ibrahim rigged up the booby-trapped sideboard at the alleged "bomb factory" at Curtis House, New Southgate, north London.
Mr Asiedu said he returned to the tower block on the evening of 21 July to sleep after dumping his rucksack device in parkland in Little Wormwood Scrubs.
But the following day he said he opened the sideboard after remembering seeing Mr Ibrahim kneeling by it on the morning of the alleged plot.
Mr Asiedu said he then left the flat and "chucked" the detonator away.
"When I was leaving Curtis House there was a police car coming," he said. "I was just walking away. I just wanted to get away."
The other men on trial with Mr Asiedu, of no fixed abode, and Mr Ibrahim, 29, of Stoke Newington, north London, are: Ramzi Mohammed, 25 and Yassin Omar, 26, of New Southgate, north London; Hussein Osman 28, also of no fixed address; and Adel Yahya, 24, of Tottenham, north London.
The prosecution have alleged the men set out to target London's transport network as part of an extremist Muslim plot but the devices failed to successfully detonate.
It is also alleged that Mr Asiedu was the fifth bomber but lost his nerve.
He has admitted helping to buy dozens of litres of hydrogen peroxide, but claims he did not know what they were to be used for.
Mr Ibrahim claimed the plan was only to set off fake bombs as part of a protest.