He put his brother in charge of all footballing matters and, despite repeated failings in the transfer window, never ever got rid of him.
He brought in swathes of random French third/fourth tier players with the hopes of flipping them for profit because their agents were his mates or potentially even himself, so there was little to no scouting done on the quality of these players.
He stuck Queensy Menig on £15k per week or something ridiculous in League One.
He went into the dressing room on multiple occasions to berate players, completely undermining any manager in place at the time.
He stuck his mate, Selim, in charge of the club for two months.
He repeatedly lied to fans, promising five year plans and detailed strategies of things he would change at the club and never delivered.
He was at the club for four and a half years and hired 11 managers in that time, so either his recruitment process was shite or his patience was shite.
He kept Barry Owen employed for the majority of his time at the club, despite Owen being at the scene of the crime for the previous regime's disastrous end.
The Abdallah timeline is here for you to remind yourself.
I do genuinely believe that he bought a club that was in a far worse condition than he anticipated when he took over, which was probably partially due to a lack of due diligence on his part but also due to the previous owners hiding certain things to ensure a sale could happen. But Abdallah wasn't just some unfortunate guy who took over a mess that nobody could make work - he was a fucking idiot who was as instrumental in Oldham's decline into the National League as anybody else, perhaps more so in many ways.
Frank has taken the club over in a far worse state, because it's got both the damage of the pre-Abdallah era and also the Abdallah era itself to repair, and has shown himself to be a competent businessman by making Oldham a sustainable business in the space of two years. Fans have returned in droves because an owner they like and respect, a man from the local area who loves Oldham, in charge, who we can see demonstrably has a long term vision of how to keep the club afloat. Abdallah had the club on the brink of insolvency on multiple occasions.